CVE-2010-3765
CRITICALCISA KEVEPSS 100th pctlDescription
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.
How to fix
Actively exploited, no published fix found yet
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Federal remediation due: 2025-10-27
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
Mozilla Multiple Products Remote Code Execution Vulnerability
Mozilla Firefox, SeaMonkey, and Thunderbird contain an unspecified vulnerability when JavaScript is enabled. This 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.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Remediation due: 2025-10-27
References
Related Vulnerabilities
Other CWE-119 (Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-4966 | Critical | 9.4 | 100% | KEV + Ransom | Fix |
| CVE-2017-11882 | High | 7.8 | 100% | KEV + Ransom | - |
| CVE-2020-0796 | Critical | 10.0 | 100% | KEV + Ransom | - |
| CVE-2008-4250 | Critical | 9.8 | 99% | KEV | - |
| CVE-2017-15944 | Critical | 9.8 | 98% | KEV | Fix |
| CVE-2015-0014 | High | 10.0 | 97% | - | - |
Common questions
How do I fix CVE-2010-3765?
No published fix for CVE-2010-3765 has been found yet. It is on the CISA Known Exploited Vulnerabilities list; federal agencies must remediate by 2025-10-27. Apply the vendor's mitigations per CISA's guidance.
Is CVE-2010-3765 being actively exploited?
Yes. CVE-2010-3765 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. US federal agencies were required to remediate it by 2025-10-27. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2010-3765?
CVE-2010-3765 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
Embed a live status badge for CVE-2010-3765
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-22.