1. Executive Summary

In late March 2025, Google released an urgent security update for its Chrome browser to address CVE-2025-2783, a high-severity zero-day vulnerability confirmed to be actively exploited in the wild. Rated 8.3 on the CVSS v3.1 scale, this flaw specifically affects Google Chrome installations on the Windows operating system. The vulnerability resides within Chrome's Mojo Inter-Process Communication (IPC) framework, stemming from the provision of an incorrect resource handle under certain conditions, ultimately enabling attackers to bypass the browser's critical sandbox protection.  

Evidence indicates that CVE-2025-2783 was leveraged as part of a sophisticated exploit chain in a cyber-espionage campaign dubbed "Operation ForumTroll". This campaign targeted specific entities within Russia, including media outlets, educational institutions, and government organizations, using phishing emails containing malicious links. Successful exploitation allowed attackers, assessed to be a state-sponsored Advanced Persistent Threat (APT) group, to escape the browser sandbox and deploy malware for espionage purposes. 

The primary mitigation strategy is the immediate application of Google's security update. The patch was included in Chrome version 134.0.6998.177/.178 for Windows, released on March 25, 2025. Due to the confirmed active exploitation, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) promptly added CVE-2025-2783 to its Known Exploited Vulnerabilities (KEV) catalog, mandating patching for federal agencies. The rapid sequence of discovery by Kaspersky researchers, reporting to Google, patch development and release, and inclusion in the CISA KEV catalog points to effective coordination within the vulnerability disclosure ecosystem. However, the fact that exploitation occurred before the patch became available underscores the persistent danger posed by zero-day threats, even with relatively swift response mechanisms.

2. CVE-2025-2783: Unpacking the Chrome Zero-Day

Identification and Severity

The vulnerability is officially tracked as CVE-2025-2783. It is classified as High severity, reflected by its CVSS v3.1 base score of 8.3. The corresponding CVSS vector, CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H, indicates the following characteristics: requires Network access for exploitation, involves High attack complexity, requires No privileges on the target system, necessitates User interaction (like clicking a link), results in a Scope change (breaking out of the sandbox), and has a High impact on Confidentiality, Integrity, and Availability.   

The vulnerability was discovered and reported to Google on March 20, 2025, by security researchers Boris Larin (@oct0xor) and Igor Kuznetsov (@2igosha) from Kaspersky. 

Context: First 2025 Exploited Chrome Zero-Day

CVE-2025-2783 holds the distinction of being the first actively exploited zero-day vulnerability affecting Google Chrome publicly disclosed in 2025. This stands in contrast to the year 2024, during which Google addressed approximately ten zero-day vulnerabilities in Chrome that were either exploited in the wild or demonstrated during hacking competitions like Pwn2Own. 

The initial decrease in the frequency of exploited Chrome zero-days at the beginning of 2025, compared to the preceding year, might have suggested improvements in Google's preventative security measures or potential shifts in attacker priorities. However, the emergence of CVE-2025-2783 serves as a stark reminder that Chrome, with its vast user base and complex architecture, remains a prime target for sophisticated adversaries. While significant efforts have been made to harden core components like the V8 JavaScript engine through initiatives like the V8 Sandbox and MiraclePtr , this vulnerability demonstrates that attackers are actively probing and successfully finding exploitable flaws in other critical subsystems, such as the Mojo IPC framework.  

3. Technical Analysis: The Mojo IPC Flaw

The Role of Mojo IPC in Chrome

Mojo is a fundamental component within the Chromium project, providing a collection of runtime libraries that enable platform-agnostic Inter-Process Communication (IPC). This IPC mechanism is crucial for Chrome's multi-process architecture, which isolates different browser functions into separate processes (e.g., browser process, renderer processes, GPU process, utility processes) for stability and security. Mojo facilitates the necessary message passing and data sharing between these distinct processes, allowing them to coordinate tasks such as rendering web pages, handling user input, and interacting with hardware, all while maintaining process isolation boundaries. The importance of Mojo in Chrome's security model is underscored by previous vulnerabilities found within its message processing capabilities, such as CVE-2024-9954 (a use-after-free flaw).

Vulnerability Mechanism

Google's official description characterizes CVE-2025-2783 as an "Incorrect handle provided in unspecified circumstances in Mojo on Windows". Kaspersky researchers elaborated, describing the root cause as a "logical error at the intersection of Google Chrome's sandbox and the Windows operating system". This vulnerability is specific to the Windows implementation of Chrome, indicating that the flaw arises from the interaction between the cross-platform Mojo framework and Windows-specific operating system features related to process management and resource access control, specifically OS handles.   

While Google restricted full technical details following standard practice for actively exploited vulnerabilities , the available descriptions suggest a scenario where the Mojo IPC mechanism on Windows could be manipulated. A less privileged process, such as a sandboxed renderer process compromised by malicious web content, could potentially trick the more privileged browser process into improperly granting access to, or misinterpreting, a Windows OS resource handle. This mishandling of handles effectively undermines the isolation enforced by the sandbox. Further supporting this interpretation, Mozilla developers, investigating in response to the Chrome disclosure, identified a similar flaw pattern (CVE-2025-2857) in Firefox on Windows, where attackers could "confuse the parent process into leaking handles into unpriviled [sic] child processes".   

The nature of this vulnerability—a logical flaw in the interaction between a cross-platform component and OS-specific security primitives—highlights the inherent complexities and potential security pitfalls at these integration points. Ensuring secure communication and resource handling across different privilege levels and between browser components and the host OS remains a significant challenge.

Sandbox Escape Explained

The Chrome sandbox is a critical security feature designed to isolate web content and the processes that render it (renderer processes) from the underlying operating system. This containment strategy aims to limit the potential damage if a renderer process is compromised, preventing malicious code from directly accessing sensitive user data or system resources.

CVE-2025-2783 directly subverts this protection. By exploiting the flaw in Mojo's handling of Windows handles during IPC, an attacker who has already achieved code execution within a sandboxed process can break out of this restricted environment. Kaspersky's description that the exploit allowed attackers to bypass the sandbox "as if it didn't even exist," without resorting to "obviously malicious or forbidden" actions, emphasizes the subtlety and effectiveness of exploiting this logical error. The vulnerability essentially creates an unintended pathway through the sandbox boundary via the IPC mechanism itself.

4. Impact Assessment

Consequences of Sandbox Evasion

The primary impact of successfully exploiting CVE-2025-2783 is the sandbox escape itself. This allows attacker-controlled code, initially confined within the limited environment of a sandboxed process (e.g., a renderer), to execute commands on the underlying Windows operating system with the privileges of the logged-in user.  

Once the sandbox is bypassed, the attacker can potentially perform a wide range of malicious actions, depending on the user's privilege level. These actions can include:

• Installing persistent malware, spyware, or ransomware.   
• Accessing, modifying, or exfiltrating sensitive user data, such as login credentials, financial information, browsing history, or local files.    
• Altering system configurations or security settings.  
• Creating new user accounts with administrative rights (if the compromised user has such privileges).   
• Establishing a foothold for further lateral movement within a compromised network. 
   

The Need for Exploit Chaining

It is crucial to understand that CVE-2025-2783, while critical for bypassing the sandbox, was utilized as part of a larger exploit chain in the observed attacks. The sandbox escape vulnerability itself typically does not provide the initial means to execute arbitrary code within the browser's renderer process. 

Kaspersky confirmed that the "Operation ForumTroll" campaign combined the CVE-2025-2783 sandbox escape with at least one additional, preceding exploit designed to achieve Remote Code Execution (RCE) within the sandboxed environment. This initial RCE vulnerability, likely targeting a component like the V8 JavaScript engine or another part of the rendering pipeline exposed to web content, was necessary to gain the initial foothold inside the sandbox. Kaspersky was unable to obtain this initial RCE exploit during their investigation.   

Therefore, a complete compromise via this attack vector required attackers to successfully leverage at least two distinct vulnerabilities: one for initial RCE within the sandbox, followed by CVE-2025-2783 to break out of the sandbox and gain broader system access. Importantly, patching CVE-2025-2783 effectively disrupts this specific attack chain by closing the sandbox escape route, even if the initial RCE vulnerability remains unpatched or unknown.   

The necessity of chaining multiple exploits underscores the value of defense-in-depth security architectures like Chrome's sandbox. Although CVE-2025-2783 demonstrated that the sandbox is not impenetrable, its presence significantly increased the complexity and resource requirements for attackers. They needed to discover and weaponize at least two vulnerabilities instead of just one, increasing the potential points of failure for the attack and the opportunities for detection or mitigation.

5. Exploitation in the Wild: Operation ForumTroll

Confirmation of Active Exploitation

Upon releasing the security update, Google explicitly acknowledged that it was "aware of reports that an exploit for CVE-2025-2783 exists in the wild". This confirmation was based on the discovery and reporting by Kaspersky researchers, who had identified the vulnerability being actively used in targeted attacks.  

Campaign Modus Operandi

Kaspersky tracked the campaign leveraging this zero-day under the moniker "Operation ForumTroll". The attack methodology involved several distinct stages:   

• Delivery: Attackers distributed phishing emails containing personalized, short-lived malicious links. The ephemeral nature of the links likely aimed to evade detection by security scanners and limit analysis opportunities.  
• Lure: The phishing emails employed social engineering, impersonating organizers of a legitimate scientific and expert forum known as "Primakov Readings". The emails contained invitations seemingly related to this event.   
• Infection Vector: Compromise occurred when a victim, using a vulnerable version of Google Chrome on Windows, clicked one of the malicious links. This action directed the browser to an attacker-controlled website (identified in some reports as using the domain primakovreadings[.]info ) hosting the exploit chain. No further user interaction was required beyond clicking the link, indicating a drive-by compromise scenario.  
• Exploit Execution: The malicious website presumably delivered the initial RCE exploit followed by the CVE-2025-2783 sandbox escape exploit.
• Targets: The campaign exhibited specific targeting, focusing on organizations within Russia. Identified victims included media outlets, educational institutions, and government organizations.  
• Goal: Based on analysis of the sophisticated malware payload deployed after successful exploitation, Kaspersky assessed the primary objective of the campaign to be espionage.   

Attribution Insights

Kaspersky characterized the attack as "technically sophisticated" and attributed it to a state-sponsored Advanced Persistent Threat (APT) group. This assessment was based on the complexity of the zero-day exploit chain, the functionality of the deployed malware, and the targeted nature of the campaign. While the specific threat actor was not publicly named in the provided materials, the combination of factors strongly points towards a well-resourced group with objectives aligned with nation-state interests.  

The specific targeting of Russian entities, the espionage objective, and the use of advanced capabilities like a Chrome zero-day exploit chain align closely with patterns typically associated with geopolitical cyber operations conducted by nation-states for intelligence gathering purposes.

6. Remediation and Mitigation Strategies

Affected and Patched Versions

Addressing CVE-2025-2783 and related risks requires updating affected web browsers promptly.

• Google Chrome: Versions prior to 134.0.6998.177/.178 for Windows are vulnerable. The patch was incorporated into versions 134.0.6998.177 and 134.0.6998.178, released on March 25, 2025.Mobile versions of Chrome using different rendering engines (like WebKit on iOS) were not affected by this specific vulnerability.
    
• Chromium-Based Browsers:As these browsers (Microsoft Edge, Brave, Opera, Vivaldi) share the underlying Chromium engine and Mojo component, they were also vulnerable. Vendors released patches shortly after Google:
  • Microsoft Edge was patched in version 134.0.3124.93 (released March 26).  
     
  • Brave and Vivaldi released updates on March 26.   
  • Opera released updates on March 27, requiring backporting of the fix. 
    
    
• Mozilla Firefox / Tor Browser: While not vulnerable to CVE-2025-2783 itself, the investigation prompted by the Chrome flaw led Mozilla developers to discover a similar vulnerability (tracked as CVE-2025-2857) in their own IPC code on Windows. This related flaw, involving incorrect handle leaking leading to potential sandbox escape, was patched in Firefox 136.0.4, Firefox ESR 115.21.1, Firefox ESR 128.8.1 (released March 28), and corresponding Tor Browser versions. There was no evidence CVE-2025-2857 was exploited in the wild.   
   

The following table summarizes the patching status for major browsers concerning CVE-2025-2783 and the related Firefox flaw as of late March 2025:

Table 1: Patch Status for CVE-2025-2783 & Related Flaws (Late March 2025)

Official Recommendations

Consistent recommendations were issued by Google, security researchers, and government agencies:

• Update Immediately: The most critical step is to update Chrome and other affected Chromium-based browsers to the patched versions as soon as possible.   
• Enable Automatic Updates: Ensure that the browser's automatic update feature is enabled to facilitate timely patching of future vulnerabilities.  
• Relaunch Browser: After checking for updates or allowing an automatic update, relaunch the browser to ensure the patch is fully applied.  
• User Awareness Training: Given the phishing vector used in Operation ForumTroll, reinforcing user awareness about the dangers of clicking unsolicited links or opening attachments is crucial.   

Regulatory Context

The severity and active exploitation of CVE-2025-2783 led to its inclusion in CISA's Known Exploited Vulnerabilities (KEV) catalog on March 27, 2025. This listing mandated that U.S. Federal Civilian Executive Branch (FCEB) agencies apply the necessary patches by April 17, 2025. This action highlights the significant risk posed by the vulnerability and serves as a strong recommendation for all organizations to prioritize patching.

The discovery of the related flaw CVE-2025-2857 in Firefox, prompted directly by the analysis of CVE-2025-2783, suggests that the underlying pattern of mishandling IPC resource handles on Windows might represent a broader vulnerability class. The specific interaction between browser IPC mechanisms and the Windows OS appears to contain subtle complexities that could be susceptible to exploitation across different browser implementations, warranting careful review by browser developers.

7. Further Analysis and Resources

Key Research Contributions

Several entities played crucial roles in the discovery, analysis, and response to CVE-2025-2783:

• Kaspersky: Credited with the initial discovery of the vulnerability through detection of the "Operation ForumTroll" campaign. They reported the flaw to Google, provided the initial public analysis linking it to espionage, described the sandbox bypass mechanism, and highlighted the need for exploit chaining. They indicated plans to release more detailed technical analysis once patching was widespread.   
• Google: Acknowledged the zero-day exploitation, developed and rapidly released the security patch (version 134.0.6998.177/.178), and communicated the update via the official Chrome Releases Blog. As per standard procedure, they initially restricted access to detailed bug information. 
• Mozilla: Proactively investigated their codebase following the CVE-2025-2783 disclosure, leading to the discovery and patching of the similar vulnerability CVE-2025-2857 in Firefox. 
   

   

References for Deeper Dives

Individuals seeking more detailed information can consult the following resources:

• Google Chrome Releases Blog: Official announcement of the patch and vulnerability details.  
• Kaspersky Securelist / Blog: Analysis of Operation ForumTroll and insights into the vulnerability.  
• NVD (National Vulnerability Database) / CVE Mitre: Official CVE entry, CVSS score, and description.   CISA Known Exploited Vulnerabilities (KEV) Catalog: Confirmation of active exploitation and patching deadlines for federal agencies. 
• Security News Outlets: Numerous articles from sources like BleepingComputer, The Hacker News, Help Net Security provide summaries, context, and timelines.  
• Simulated Proof-of-Concept (GitHub): A non-exploiting, educational PoC simulating aspects of CVE-2025-2783 exists for training and detection engineering purposes.  

The availability of information from these diverse sources—vendor advisories, researcher reports, government alerts, vulnerability databases, and security news analysis—creates a valuable ecosystem for defenders. Even when vendors initially restrict deep technical details, this multi-channel approach allows organizations to gather intelligence, assess risk (e.g., using CISA KEV status), prioritize remediation actions, and understand the broader context of the threat landscape.

8. Conclusion

CVE-2025-2783 represents a significant security event, marking the first actively exploited Google Chrome zero-day vulnerability disclosed in 2025. This high-severity flaw in the Mojo IPC framework allowed attackers to bypass Chrome's sandbox on Windows systems, a critical security boundary. The real-world risk was clearly demonstrated by the "Operation ForumTroll" campaign, where a suspected state-sponsored APT group leveraged this vulnerability in an exploit chain to conduct espionage against targeted organizations in Russia.  

The vulnerability's root cause—a logical error in how Chrome's cross-platform IPC mechanism interacted with Windows-specific handle management—highlights the persistent challenges in securing complex software components, particularly at the interface between the browser and the underlying operating system. The subsequent discovery of a similar flaw (CVE-2025-2857) in Firefox further suggests that this interaction point may constitute a broader class of potential weaknesses deserving continued scrutiny across browser implementations on Windows.  

The exploitation of CVE-2025-2783, despite Chrome's robust sandboxing architecture, underscores that no single security layer provides absolute protection. Sophisticated attackers continuously probe for and find weaknesses in complex software interactions. This incident reinforces the necessity of a defense-in-depth strategy, combining architectural defenses like sandboxing with rapid vulnerability patching, vigilant threat monitoring, and robust user security awareness programs. For organizations and individual users, the key takeaways are the critical importance of applying security updates immediately upon availability, ensuring automatic update mechanisms are functional, and maintaining caution regarding potential phishing attempts. Continuous vigilance and proactive security posture management remain essential defenses against the evolving landscape of zero-day threats targeting ubiquitous software like web browsers.