CVE-2026-2773 Overview
CVE-2026-2773 is a critical boundary condition vulnerability affecting the Web Audio component in Mozilla Firefox and Thunderbird. The flaw stems from incorrect boundary conditions that could potentially allow attackers to compromise affected systems through network-based attacks. This vulnerability impacts multiple versions of Firefox and Thunderbird, including both standard and Extended Support Release (ESR) editions.
Critical Impact
Incorrect boundary conditions in the Web Audio component could allow remote attackers to potentially execute arbitrary code or cause system compromise without user interaction.
Affected Products
- Mozilla Firefox < 148
- Mozilla Firefox ESR < 115.33
- Mozilla Firefox ESR < 140.8
- Mozilla Thunderbird < 148
- Mozilla Thunderbird < 140.8
Discovery Timeline
- 2026-02-24 - CVE-2026-2773 published to NVD
- 2026-02-25 - Last updated in NVD database
Technical Details for CVE-2026-2773
Vulnerability Analysis
The vulnerability resides in the Web Audio component of Mozilla Firefox and Thunderbird. Web Audio API provides a powerful system for controlling audio on the web, allowing developers to choose audio sources, add effects, create visualizations, and more. The incorrect boundary conditions in this component create a situation where input validation fails to properly constrain data within expected limits.
Boundary condition errors typically occur when software fails to properly validate the boundaries of data being processed, which can lead to memory corruption, buffer overflows, or other exploitable conditions. In this case, the Web Audio component's failure to properly enforce boundary conditions creates an exploitable attack surface that can be triggered remotely via network access.
The vulnerability requires no privileges and no user interaction to exploit, making it particularly dangerous for internet-facing browser deployments. An attacker could potentially craft malicious web content that triggers the boundary condition error when processed by the Web Audio component.
Root Cause
The root cause of CVE-2026-2773 is improper boundary validation within the Web Audio component's data processing routines. When audio data or related parameters exceed expected boundaries, the component fails to properly handle these edge cases, potentially leading to memory safety issues. This type of vulnerability often results from insufficient input validation or missing bounds checks in low-level audio processing code.
Attack Vector
The attack vector for this vulnerability is network-based, requiring no authentication or user interaction. An attacker could exploit this vulnerability by:
- Hosting malicious content on a website that utilizes the Web Audio API
- Enticing a victim to visit the malicious page, or delivering the payload through compromised legitimate websites
- The malicious audio content triggers the boundary condition error in the victim's browser
- Successful exploitation could lead to arbitrary code execution within the context of the browser process
For Thunderbird users, the attack could be delivered through malicious email content containing HTML that leverages the Web Audio API. For technical details on the specific implementation flaw, see the Mozilla Bug Report #2014832.
Detection Methods for CVE-2026-2773
Indicators of Compromise
- Unexpected browser crashes or hangs when processing audio content
- Unusual memory consumption by Firefox or Thunderbird processes
- Suspicious network connections originating from browser processes
- Web Audio API calls with abnormal parameters in browser debug logs
Detection Strategies
- Monitor for anomalous Web Audio API usage patterns in web traffic
- Implement browser version detection to identify unpatched installations
- Deploy endpoint detection rules for unusual browser process behavior
- Review web proxy logs for connections to known malicious domains serving exploit content
Monitoring Recommendations
- Enable enhanced logging for browser processes on critical systems
- Configure SentinelOne agents to monitor for browser memory corruption indicators
- Implement network-level detection for malicious JavaScript patterns targeting Web Audio
- Conduct regular audits of Firefox and Thunderbird versions across the enterprise
How to Mitigate CVE-2026-2773
Immediate Actions Required
- Update Firefox to version 148 or later immediately
- Update Firefox ESR to version 115.33 or 140.8 or later
- Update Thunderbird to version 148 or 140.8 or later
- Consider temporarily disabling the Web Audio API if updates cannot be applied immediately
Patch Information
Mozilla has released security patches addressing this vulnerability across multiple product versions. Organizations should prioritize updating to the following minimum versions:
- Firefox: Version 148 or later
- Firefox ESR: Version 115.33 or 140.8 or later
- Thunderbird: Version 148 or 140.8 or later
For complete patch details, refer to the Mozilla Security Advisories:
Workarounds
- Disable JavaScript execution for untrusted websites using browser settings or extensions
- Use content security policies to restrict Web Audio API access on enterprise web applications
- Implement browser isolation solutions for high-risk browsing activities
- Consider using alternative browsers until patches can be applied
# Verify Firefox version from command line
firefox --version
# Verify Thunderbird version from command line
thunderbird --version
# For enterprise deployments, use automated update mechanisms
# or deploy via package managers to ensure consistent patching
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
