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 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.
do firstApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Can a WAF block it? No. The vulnerability is triggered by JavaScript code executed in the browser, which is delivered via HTTP requests such as web pages. The malicious input looks like normal JavaScript and web content, so a web application firewall cannot reliably distinguish it from legitimate traffic.
Also consider: patch
Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2010-3765 being exploited?
Yes. CVE-2010-3765 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2010-3765?
CVE-2010-3765 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2010-3765?
Yes. A fix has been recorded for CVE-2010-3765. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2010-3765 affect?
CVE-2010-3765 affects mozilla:firefox, mozilla:thunderbird, mozilla:seamonkey. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
public exploits
Public exploit code: 4 on Exploit-DB · 1 Metasploit module
- Mozilla Firefox - Interleaving 'document.write' / 'appendChild' (Metasploit) · remote · 22 Feb 2011 · verified
- Mozilla Firefox 3.6.8 < 3.6.11 - Interleaving 'document.write' / 'appendChild' Remote Overflow · remote · 29 Oct 2010 · verified
- Mozilla Firefox - Interleaving 'document.write' / 'appendChild' Denial of Service · dos · 28 Oct 2010 · verified
- Mozilla Firefox - Simplified Memory Corruption (PoC) · dos · 28 Oct 2010 · verified
- exploit/windows/browser/mozilla_interleaved_write · exploit · normal
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
cisa ssvc
- exploitation
- active
- automatable
- yes
- technical impact
- total
Assessed by CISA 4 Oct 2025 (SSVC 2.0.3).
timeline
- 28 Oct 2010First public exploit or proof of concept
- 28 Oct 2010Published · same day later
- 4 Oct 2025CISA SSVC assessment: exploitation active · 5,455 days (about 15 years) later
- 6 Oct 2025Added to CISA KEV (exploited in the wild) · 2 days later
- 22 Oct 2025CVE record last updated · 16 days later
- 27 Oct 2025CISA remediation due date (US federal agencies) · 5 days later
- 2 Nov 2026Analysed by vulneraibility.com · 372 days (about 1 year) later
- Advisoryrhn.redhat.com /errata/RHSA-2010-0812.html
- Advisorysecunia.com /advisories/41965
- Advisorysecunia.com /advisories/41975
- Advisoryredhat.com /support/errata/RHSA-2010-0896.html
- Advisoryredhat.com /support/errata/RHSA-2010-0808.html
- Advisorysecunia.com /advisories/41761
- Advisorylists.fedoraproject.org /pipermail/package-announce/2010-November/050233.html
- Advisorysecunia.com /advisories/41969
Show 42 more
- Advisoryubuntu.com /usn/USN-1011-3
- Advisoryubuntu.com /usn/usn-1011-1
- Advisoryubuntu.com /usn/USN-1011-2
- Advisoryredhat.com /support/errata/RHSA-2010-0809.html
- Advisorymandriva.com /security/advisories?name=MDVSA-2010:219
- Advisorysecunia.com /advisories/42867
- Advisorydebian.org /security/2010/dsa-2124
- Advisorysecunia.com /advisories/42043
- Advisorysecunia.com /advisories/41966
- Advisorymandriva.com /security/advisories?name=MDVSA-2010:213
- Advisorysecunia.com /advisories/42008
- Advisorylists.fedoraproject.org /pipermail/package-announce/2010-October/050061.html
- Advisoryslackware.com /security/viewer.php?l=slackware-security&y=2010&m=slackware-security.556706
- Advisoryredhat.com /support/errata/RHSA-2010-0810.html
- Advisorysecunia.com /advisories/42003
- Advisorylists.fedoraproject.org /pipermail/package-announce/2010-October/050077.html
- Advisoryredhat.com /support/errata/RHSA-2010-0861.html
- Advisorylists.fedoraproject.org /pipermail/package-announce/2010-October/050154.html
- Exploitexploit-db.com /exploits/15341
- Exploitexploit-db.com /exploits/15352
- Exploitexploit-db.com /exploits/15342
- Linksecurityfocus.com /bid/44425
- Linkbugzilla.mozilla.org /show_bug.cgi?id=607222#c53
- Linkvupen.com /english/advisories/2010/2837
- Linkbugzilla.redhat.com /show_bug.cgi?id=646997
- Linksupport.avaya.com /css/P8/documents/100114335
- Linksecuritytracker.com /id?1024651
- Linkbugzilla.mozilla.org /show_bug.cgi?id=607222
- Linknorman.com /about_norman/press_center/news_archive/2010/129223/en?utm_source=twitterfeed&ut
- Linkblogs.sun.com /security/entry/multiple_vulnerabilities_in_mozilla_firefox
- Linknorman.com /about_norman/press_center/news_archive/2010/129223/
- Linksecuritytracker.com /id?1024650
- Linkblog.mozilla.com /security/2010/10/26/critical-vulnerability-in-firefox-3-5-and-firefox-3-6/
- Linkvupen.com /english/advisories/2010/2857
- Linkvupen.com /english/advisories/2011/0061
- Linksupport.avaya.com /css/P8/documents/100114329
- Linksecuritytracker.com /id?1024645
- Linknorman.com /security_center/virus_description_archive/129146/
- Linkvupen.com /english/advisories/2010/2871
- Linkisc.sans.edu /diary.html?storyid=9817
- Linkmozilla.org /security/announce/2010/mfsa2010-73.html
- Linkoval.cisecurity.org /repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12108
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Exploit-DB: published exploits
- Metasploit Framework: exploit and scanner modules
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.