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Mozilla released Firefox 157 with fixes for 76 vulnerabilities, including 38 rated high severity. The high-severity issues include memory-safety flaws that could allow attacker-controlled code execution if a user opens a specially crafted web page; Mozilla reported no vulnerabilities rated critical and the available advisories do not identify active exploitation.
Mozilla also issued security updates for Firefox ESR 153.4.0, 140.17.0, and 115.42.0. Users and administrators running earlier Firefox or ESR versions should upgrade promptly. Firefox 157 additionally introduces the experimental Nova sidebar interface, enables AV1 screen sharing support in WebRTC, and includes CSS and JavaScript dialog improvements.
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Mozilla published a security advisory covering the vulnerabilities fixed in Firefox 157 and the corresponding ESR releases. Guyana National CIRT advised users and administrators to review and apply the updates where necessary.
Firefox 157 remediates 76 vulnerabilities, including 38 rated high severity; none were classified as critical. Some high-severity issues are memory-safety flaws that could potentially permit code execution if a victim opens a specially crafted web page.
Mozilla released Firefox 157 along with Firefox ESR 153.4/153.4.0, 140.17/140.17.0, and 115.42/115.42.0. The updates address vulnerabilities affecting earlier Firefox and ESR versions.
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Mozilla released **Firefox 155** and maintenance updates for Firefox ESR 153.2.0, 140.15.0, and 115.40.0. The release remediates **109 security vulnerabilities**, including memory-safety issues that malicious websites could potentially exploit for arbitrary code execution or other browser compromise; organizations should prioritize deployment across managed Firefox installations. Firefox 155 also introduces an experimental AI-assisted “Smart Window” feature for a limited user set, alongside web-platform, developer-tool, PDF viewer, Android, HTTP/3, WebAssembly, CSS, JSON, WebTransport, and Windows controller updates. Several experimental platform capabilities remain disabled by default and can be enabled through `about:config`; the release also changes captive-portal detection from `detectportal.firefox.com` to `firefox-portal-detection.com`.
Sep 5, 2026
Mozilla released **Firefox 152** for desktop and web platforms alongside **Firefox ESR 140.12.0** and **115.37.0**, delivering browser, developer, and mobile updates that include experimental **JPEG XL** support in Firefox Labs, changes to the Notifications and Pointer Lock APIs, `CSS field-sizing`, PDF handling improvements, and new Android features such as AI-assisted tab grouping and enhanced link-sharing options. The release also fixes **77 security vulnerabilities**, with Mozilla stating that **60** were memory-safety bugs and that some could potentially be exploited for **arbitrary code execution** when processing specially crafted content. The patched issues include groups tracked as **`CVE-2026-12328`**, **`CVE-2026-12327`**, and **`CVE-2026-12326`**, making the update a significant security release for both standard and ESR Firefox users.
Jul 12, 2026
Mozilla released **Firefox 156** and **Firefox ESR 153.3** to address security vulnerabilities in its browser products. The Canadian Centre for Cyber Security advisory `AV26-924` identifies Firefox versions earlier than 156 and Firefox ESR versions earlier than **115.41**, **140.16**, and **153.3** as affected. Organizations should update standard Firefox deployments to version 156 and move ESR deployments to the applicable fixed release—115.41, 140.16, or 153.3. Administrators should review Mozilla’s associated security advisories, including `MFSA-2026-90` and `MFSA-2026-93`, and prioritize remediation across managed endpoints.
Sep 22, 2026