Description
layout/base/nsCSSFrameConstructor.cpp in the browser engine in Mozilla Firefox 3.0.x before 3.0.15 does not properly handle first-letter frames, which allows remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unspecified vectors.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 5.0 | xulrunner | 1.9.0.15-0lenny1 | DSA-1922-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5 | firefox | 3.0.15-3.el5_4 | RHSA-2009:1530 |
| RHEL 5 | nspr +1 | 4.7.6-1.el5_4 | RHSA-2009:1530 |
| RHEL 5 | xulrunner +2 | 1.9.0.15-3.el5_4 | RHSA-2009:1530 |
| RHEL 4 | firefox | 3.0.15-3.el4 | RHSA-2009:1530 |
| RHEL 4 | nspr +1 | 4.7.6-1.el4_8 | RHSA-2009:1530 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Exploit-DB 1
- Mozilla Firefox 3.0.14 - Remote Memory Corruption EDB-33314 · dos · Oct 27, 2009 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 2
- RHSA-2009:1530 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DSA-1922-1 xulrunner - several vulnerabilities Debian Security (DSA / DLA) · Mar 9, 2026
References
- oval:org.mitre.oval:def:5581 vdb-entry signature
- 272909 vendor-advisory
- oval:org.mitre.oval:def:11219 vdb-entry signature
- https://bugzilla.mozilla.org/show_bug.cgi?id=514960
- http://www.mozilla.org/security/announce/2009/mfsa2009-64.html
- ADV-2009-3334 vdb-entry