CVE-2009-1836

CVE-2009-1836 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 6.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

• Severity: Medium (CVSS 2.0 base score 6.8)
• EPSS exploit prediction: 2% (79th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-287
• Affected product: Mozilla Firefox
• Published: 2009-06-12
• Last modified: 2026-06-16

Description

Mozilla Firefox before 3.0.11, Thunderbird before 2.0.0.22, and SeaMonkey before 1.1.17 use the HTTP Host header to determine the context of a document provided in a non-200 CONNECT response from a proxy server, which allows man-in-the-middle attackers to execute arbitrary web script by modifying this CONNECT response, aka an "SSL tampering" attack.

Frequently asked questions

What is CVE-2009-1836?

Mozilla Firefox before 3.0.11, Thunderbird before 2.0.0.22, and SeaMonkey before 1.1.17 use the HTTP Host header to determine the context of a document provided in a non-200 CONNECT response from a proxy server, which allows man-in-the-middle attackers to execute arbitrary web script by modifying this CONNECT response, aka an "SSL tampering" attack.

How severe is CVE-2009-1836?

CVE-2009-1836 has a CVSS 2.0 base score of 6.8, rated medium severity.

Is CVE-2009-1836 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-1836?

CVE-2009-1836 primarily affects Mozilla Firefox. In total, 202 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-1836?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2009-1836 published?

CVE-2009-1836 was published on 2009-06-12 and last updated on 2026-06-16.

References

• http://osvdb.org/55160
• http://research.microsoft.com/apps/pubs/default.aspx?id=79323
• http://research.microsoft.com/pubs/79323/pbp-final-with-update.pdf
• http://secunia.com/advisories/35331
• http://secunia.com/advisories/35415
• http://secunia.com/advisories/35431
• http://secunia.com/advisories/35439
• http://secunia.com/advisories/35440
• http://secunia.com/advisories/35468
• http://secunia.com/advisories/35536
• http://secunia.com/advisories/35561
• http://secunia.com/advisories/35602
• http://secunia.com/advisories/35882
• http://slackware.com/security/viewer.php?l=slackware-security&y=2009&m=slackware-security.372468
• http://slackware.com/security/viewer.php?l=slackware-security&y=2009&m=slackware-security.425408
• http://sunsolve.sun.com/search/document.do?assetkey=1-66-264308-1
• http://www.debian.org/security/2009/dsa-1820
• http://www.debian.org/security/2009/dsa-1830
• http://www.mandriva.com/security/advisories?name=MDVSA-2009:141
• http://www.mozilla.org/security/announce/2009/mfsa2009-27.html
• http://www.redhat.com/support/errata/RHSA-2009-1126.html
• http://www.securityfocus.com/bid/35326
• http://www.securityfocus.com/bid/35380
• http://www.securitytracker.com/id?1022396
• http://www.slackware.com/security/viewer.php?l=slackware-security&y=2009&m=slackware-security.454275
• http://www.ubuntu.com/usn/usn-782-1
• http://www.vupen.com/english/advisories/2009/1572
• https://bugzilla.mozilla.org/show_bug.cgi?id=479880
• https://bugzilla.redhat.com/show_bug.cgi?id=503578
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11764

Affected products (202)

• cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.6:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.6.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.7:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.7.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.8:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.9:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.9:rc:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.9.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.9.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.9.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.9_rc:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.10:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:0.10.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0:preview_release:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.6:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.6:*:linux:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.7:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.0.8:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.4.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5:beta1:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5:beta2:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:1.5.0.6:*:*:*:*:*:*:*

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Browse all CWE-287 (Improper Authentication) vulnerabilities →