CVE-2026-2774 Overview
An integer overflow vulnerability has been identified in the Audio/Video component of Mozilla Firefox and Thunderbird. This memory corruption flaw affects multiple versions of both the Firefox browser and Thunderbird email client, including both standard and ESR (Extended Support Release) branches. Integer overflow vulnerabilities in media processing components are particularly dangerous as they can be triggered by visiting malicious websites or opening crafted media content.
Critical Impact
This integer overflow vulnerability in the Audio/Video component can be exploited remotely without authentication, potentially leading to complete system compromise through arbitrary code execution.
Affected Products
- Mozilla Firefox versions prior to 148
- Mozilla Firefox ESR versions prior to 115.33
- Mozilla Firefox ESR versions prior to 140.8
- Mozilla Thunderbird versions prior to 148
- Mozilla Thunderbird ESR versions prior to 140.8
Discovery Timeline
- 2026-02-24 - CVE-2026-2774 published to NVD
- 2026-02-26 - Last updated in NVD database
Technical Details for CVE-2026-2774
Vulnerability Analysis
CVE-2026-2774 is classified as CWE-190 (Integer Overflow or Wraparound), a memory corruption vulnerability that occurs when arithmetic operations produce values exceeding the maximum size that the integer type can hold. In the context of the Audio/Video component, this overflow likely occurs during buffer size calculations or media stream processing, where large or maliciously crafted input values cause the integer to wrap around to a small or negative value.
When an integer overflow occurs during memory allocation calculations, the resulting buffer may be significantly smaller than required. Subsequent operations that write data into this undersized buffer can then cause heap corruption, potentially allowing an attacker to overwrite adjacent memory regions and gain control of program execution.
The network-accessible nature of this vulnerability means attackers can craft malicious audio or video content hosted on websites or embedded in emails. When a user visits a compromised page in Firefox or opens a crafted email in Thunderbird, the vulnerable Audio/Video component processes the malicious content, triggering the overflow condition.
Root Cause
The root cause of this vulnerability is improper integer handling in the Audio/Video media processing component. When processing specially crafted media files or streams, the component performs arithmetic calculations on integer values without adequate overflow checking. This allows attackers to supply input values that, when processed, cause the integer to exceed its maximum representable value and wrap around, typically resulting in an unexpectedly small allocation size followed by out-of-bounds memory writes.
Attack Vector
This vulnerability is exploitable over the network without requiring any authentication or user privileges. An attacker can host malicious media content on a website, embed it in advertisements, or send crafted emails containing malicious audio/video attachments. The attack requires no user interaction beyond normal browsing or email reading activities.
The exploitation flow typically involves:
- Attacker crafts media content with specific parameters designed to trigger integer overflow
- User visits a webpage or opens an email containing the malicious content
- The Audio/Video component processes the media, triggering the overflow during buffer allocation
- Memory corruption occurs, potentially allowing arbitrary code execution with the privileges of the browser process
Due to the nature of this vulnerability, exploitation details are not provided. For technical specifics, refer to the Mozilla Bug Report #2014883 and the associated security advisories.
Detection Methods for CVE-2026-2774
Indicators of Compromise
- Unexpected browser or email client crashes when loading audio/video content
- Anomalous memory allocation patterns in Firefox or Thunderbird processes
- Suspicious outbound network connections from browser processes following media playback
- Core dumps or crash reports indicating memory corruption in media-related components
Detection Strategies
- Deploy endpoint detection solutions to monitor for exploitation attempts targeting browser processes
- Implement network-level inspection for malformed media content targeting known vulnerability patterns
- Monitor for unusual child process spawning from Firefox or Thunderbird applications
- Configure browser crash reporting to centrally collect and analyze crash telemetry for exploitation indicators
Monitoring Recommendations
- Enable enhanced logging for browser application events and system calls
- Monitor for processes spawned by Firefox or Thunderbird with unexpected command-line arguments
- Track network connections originating from browser processes to identify potential command-and-control activity
- Implement file integrity monitoring on browser installation directories to detect unauthorized modifications
How to Mitigate CVE-2026-2774
Immediate Actions Required
- Update Firefox to version 148 or later immediately
- Update Firefox ESR to version 115.33 or 140.8 (depending on your ESR branch)
- Update Thunderbird to version 148 or 140.8 ESR immediately
- Consider temporarily disabling automatic media playback until patches are applied
- Block access to known malicious domains delivering exploit content
Patch Information
Mozilla has released security updates addressing this vulnerability across all affected product lines. Organizations should prioritize updating to the following versions:
- Firefox: Version 148 or later
- Firefox ESR: Version 115.33 or 140.8
- Thunderbird: Version 148 or 140.8 ESR
For detailed patch information, consult the following Mozilla Security Advisories:
Workarounds
- Disable automatic media playback in Firefox via about:config settings
- Use content-blocking browser extensions to prevent automatic loading of audio/video content from untrusted sources
- Configure email clients to not automatically render HTML content or embedded media
- Implement network-level blocking of suspicious media content at the perimeter firewall
# Firefox configuration to disable automatic media playback
# Navigate to about:config and set the following preferences:
# media.autoplay.default = 5 (Block Audio and Video)
# media.autoplay.blocking_policy = 2 (Strict blocking)
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
