Red Hat Security Advisory: firefox security update
Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability. Security Fix(es): * firefox: thunderbird: Mitigation bypass in the Data Loss Prevention component (CVE-2026-74983) * firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component (CVE-2026-74934) * firefox: thunderbird: Privilege escalation in the Networking: Cookies component (CVE-2026-74953) * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74987) * firefox: thunderbird: Information disclosure in the Graphics component (CVE-2026-74948) * firefox: thunderbird: Use-after-free in the Graphics: ImageLib component (CVE-2026-74943) * firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component (CVE-2026-74971) * firefox: thunderbird: Privilege escalation in the Graphics: CanvasWebGL component (CVE-2026-74941) * firefox: Privilege escalation in the Shell Integration component (CVE-2026-74965) * firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-74946) * firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973) * firefox: thunderbird: Privilege escalation due to use-after-free in the Graphics: Canvas2D component (CVE-2026-74949) * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74990) * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-74936) * firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-74940) * firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960) * firefox: thunderbird: Use-after-free in the Layout: Text and Fonts component (CVE-2026-74969) * firefox: thunderbird: Mitigation bypass in the Storage: Cache API component (CVE-2026-74959) * firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-74976) * firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component (CVE-2026-74974) * firefox: thunderbird: Mitigation bypass in the Safe Browsing component (CVE-2026-74957) * firefox: thunderbird: Same-origin policy bypass in the Audio/Video: Playback component (CVE-2026-74967) * firefox: Privilege escalation in the Remote Settings Client component (CVE-2026-74942) * firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-74939) * firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component (CVE-2026-74972) * firefox: thunderbird: Information disclosure in the Graphics: Text component (CVE-2026-74945) * firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-74963) * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-74944) * firefox: Integer overflow in the Graphics component (CVE-2026-74964) * firefox: Site isolation issue in the Networking: Cookies component (CVE-2026-74962) * firefox: thunderbird: Privilege escalation in the DOM: Networking component (CVE-2026-74935) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
AI Analysis
Technical Summary
This Red Hat security advisory addresses a collection of 31 vulnerabilities in Mozilla Firefox and Thunderbird, including mitigation bypasses, site isolation issues, privilege escalations, information disclosures, use-after-free vulnerabilities, race conditions, integer overflows, and same-origin policy bypasses. The affected components span Graphics (CanvasWebGL, ImageLib, Canvas2D, Text), DOM (UI Events, Navigation, Push Subscriptions, Core & HTML), Networking (Cookies), JavaScript engine (JIT, WebAssembly), Storage (Cache API), Safe Browsing, Shell Integration, Remote Settings Client, and WebExtensions. The advisory references fixes in Firefox ESR versions 115.39, 140.14, 153.1, and Firefox 154. The update is rated as having an Important security impact by Red Hat and addresses multiple CVEs including CVE-2026-74934, CVE-2026-74935, CVE-2026-74936, and others up to CVE-2026-74990. No CVSS scores are provided in the advisory; users are directed to individual CVE pages for detailed scoring and impact information.
Potential Impact
The vulnerabilities collectively could allow attackers to bypass mitigations, escalate privileges, disclose sensitive information, bypass same-origin policies, and cause use-after-free conditions leading to potential arbitrary code execution or denial of service. The issues affect core browser and email client components, potentially impacting confidentiality, integrity, and security boundaries within the affected applications. The advisory rates the overall impact as Important, indicating significant security concerns that warrant prompt attention.
Mitigation Recommendations
Red Hat has released updated Firefox packages for Red Hat Enterprise Linux 8 and its variants that address these vulnerabilities. Users should apply the security update as soon as possible following Red Hat's published guidance at https://access.redhat.com/articles/11258. No additional mitigation steps are noted beyond applying the official update. Patch status is confirmed as fixed in the updated packages provided by Red Hat.
Red Hat Security Advisory: firefox security update
Description
Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability. Security Fix(es): * firefox: thunderbird: Mitigation bypass in the Data Loss Prevention component (CVE-2026-74983) * firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component (CVE-2026-74934) * firefox: thunderbird: Privilege escalation in the Networking: Cookies component (CVE-2026-74953) * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74987) * firefox: thunderbird: Information disclosure in the Graphics component (CVE-2026-74948) * firefox: thunderbird: Use-after-free in the Graphics: ImageLib component (CVE-2026-74943) * firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component (CVE-2026-74971) * firefox: thunderbird: Privilege escalation in the Graphics: CanvasWebGL component (CVE-2026-74941) * firefox: Privilege escalation in the Shell Integration component (CVE-2026-74965) * firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-74946) * firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973) * firefox: thunderbird: Privilege escalation due to use-after-free in the Graphics: Canvas2D component (CVE-2026-74949) * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74990) * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-74936) * firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-74940) * firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960) * firefox: thunderbird: Use-after-free in the Layout: Text and Fonts component (CVE-2026-74969) * firefox: thunderbird: Mitigation bypass in the Storage: Cache API component (CVE-2026-74959) * firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-74976) * firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component (CVE-2026-74974) * firefox: thunderbird: Mitigation bypass in the Safe Browsing component (CVE-2026-74957) * firefox: thunderbird: Same-origin policy bypass in the Audio/Video: Playback component (CVE-2026-74967) * firefox: Privilege escalation in the Remote Settings Client component (CVE-2026-74942) * firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-74939) * firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component (CVE-2026-74972) * firefox: thunderbird: Information disclosure in the Graphics: Text component (CVE-2026-74945) * firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-74963) * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-74944) * firefox: Integer overflow in the Graphics component (CVE-2026-74964) * firefox: Site isolation issue in the Networking: Cookies component (CVE-2026-74962) * firefox: thunderbird: Privilege escalation in the DOM: Networking component (CVE-2026-74935) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This Red Hat security advisory addresses a collection of 31 vulnerabilities in Mozilla Firefox and Thunderbird, including mitigation bypasses, site isolation issues, privilege escalations, information disclosures, use-after-free vulnerabilities, race conditions, integer overflows, and same-origin policy bypasses. The affected components span Graphics (CanvasWebGL, ImageLib, Canvas2D, Text), DOM (UI Events, Navigation, Push Subscriptions, Core & HTML), Networking (Cookies), JavaScript engine (JIT, WebAssembly), Storage (Cache API), Safe Browsing, Shell Integration, Remote Settings Client, and WebExtensions. The advisory references fixes in Firefox ESR versions 115.39, 140.14, 153.1, and Firefox 154. The update is rated as having an Important security impact by Red Hat and addresses multiple CVEs including CVE-2026-74934, CVE-2026-74935, CVE-2026-74936, and others up to CVE-2026-74990. No CVSS scores are provided in the advisory; users are directed to individual CVE pages for detailed scoring and impact information.
Potential Impact
The vulnerabilities collectively could allow attackers to bypass mitigations, escalate privileges, disclose sensitive information, bypass same-origin policies, and cause use-after-free conditions leading to potential arbitrary code execution or denial of service. The issues affect core browser and email client components, potentially impacting confidentiality, integrity, and security boundaries within the affected applications. The advisory rates the overall impact as Important, indicating significant security concerns that warrant prompt attention.
Mitigation Recommendations
Red Hat has released updated Firefox packages for Red Hat Enterprise Linux 8 and its variants that address these vulnerabilities. Users should apply the security update as soon as possible following Red Hat's published guidance at https://access.redhat.com/articles/11258. No additional mitigation steps are noted beyond applying the official update. Patch status is confirmed as fixed in the updated packages provided by Red Hat.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2026:58898
- Cve Count
- 31
- Additional Cves
- ["CVE-2026-74935","CVE-2026-74936","CVE-2026-74939","CVE-2026-74940","CVE-2026-74941","CVE-2026-74942","CVE-2026-74943","CVE-2026-74944","CVE-2026-74945","CVE-2026-74946","CVE-2026-74948","CVE-2026-74949","CVE-2026-74953","CVE-2026-74957","CVE-2026-74959","CVE-2026-74960","CVE-2026-74962","CVE-2026-74963","CVE-2026-74964","CVE-2026-74965","CVE-2026-74967","CVE-2026-74969","CVE-2026-74971","CVE-2026-74972","CVE-2026-74973","CVE-2026-74974","CVE-2026-74976","CVE-2026-74983","CVE-2026-74987","CVE-2026-74990"]
- Cvss Version
- null
Threat ID: 6a8c4c48acd9273b499be016
Added to database: 08/24/2026, 13:51:04 UTC
Last enriched: 08/24/2026, 13:58:14 UTC
Last updated: 08/24/2026, 22:52:13 UTC
Views: 5
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.