CVE-2026-74981: Vulnerability in Mozilla Firefox
CVE-2026-74981 is a high-severity site isolation vulnerability in the Audio/Video: Web Codecs component of Mozilla Firefox. It was addressed and fixed in Firefox version 154 and Firefox ESR 153.1, as well as Thunderbird 154 and Thunderbird 153.1. The vulnerability could allow an attacker to bypass site isolation protections, potentially leading to high confidentiality and integrity impacts. No known exploits in the wild have been reported.
AI Analysis
Technical Summary
This vulnerability involves a site isolation issue within the Audio/Video: Web Codecs component of Mozilla Firefox. Site isolation is a security feature designed to separate different web origins into different processes to prevent data leakage or unauthorized access. The flaw could allow an attacker to bypass these isolation boundaries, impacting confidentiality and integrity. The issue was fixed in Firefox 154 and Firefox ESR 153.1, along with corresponding Thunderbird versions.
Potential Impact
The vulnerability has a CVSS 3.1 score of 8.1 (high severity) with network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, and high confidentiality and integrity impacts. This means an attacker could remotely exploit the flaw to compromise sensitive data or manipulate content within the browser context. Availability is not impacted. No active exploitation has been reported.
Mitigation Recommendations
A fix is available and has been released in Firefox 154 and Firefox ESR 153.1. Users and administrators should update affected Firefox and Thunderbird installations to these versions or later to remediate this vulnerability. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-74981: Vulnerability in Mozilla Firefox
Description
CVE-2026-74981 is a high-severity site isolation vulnerability in the Audio/Video: Web Codecs component of Mozilla Firefox. It was addressed and fixed in Firefox version 154 and Firefox ESR 153.1, as well as Thunderbird 154 and Thunderbird 153.1. The vulnerability could allow an attacker to bypass site isolation protections, potentially leading to high confidentiality and integrity impacts. No known exploits in the wild have been reported.
CVSS v3.1
Score 8.1high
Affected software
Mozilla
Firefox
Mozilla
Thunderbird
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves a site isolation issue within the Audio/Video: Web Codecs component of Mozilla Firefox. Site isolation is a security feature designed to separate different web origins into different processes to prevent data leakage or unauthorized access. The flaw could allow an attacker to bypass these isolation boundaries, impacting confidentiality and integrity. The issue was fixed in Firefox 154 and Firefox ESR 153.1, along with corresponding Thunderbird versions.
Potential Impact
The vulnerability has a CVSS 3.1 score of 8.1 (high severity) with network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, and high confidentiality and integrity impacts. This means an attacker could remotely exploit the flaw to compromise sensitive data or manipulate content within the browser context. Availability is not impacted. No active exploitation has been reported.
Mitigation Recommendations
A fix is available and has been released in Firefox 154 and Firefox ESR 153.1. Users and administrators should update affected Firefox and Thunderbird installations to these versions or later to remediate this vulnerability. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-08-17T11:59:08.402Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-74/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-77/","vendor":"Mozilla"}]
Threat ID: 6a84550bc6e8be03323676bc
Added to database: 08/18/2026, 12:50:19 UTC
Last enriched: 09/11/2026, 21:48:24 UTC
Last updated: 10/02/2026, 02:46:06 UTC
Views: 30
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