Out-of-bounds write in Mozilla Firefox - CVE-2024-29943

Vulnerability identifier: #VU87735

CSH Severity: High

CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2024-29943

CWE-ID: CWE-787

Exploitation vector: Remote access

Exploit availability: Public exploit is available

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to an error during range-based bounds check elimination when processing JavaScript objects. A remote attacker can create a specially crafted website, trick the victim into opening it, trigger an out-of-bounds write and execute arbitrary code on the target system.

Mozilla Firefox
Gentoo Linux
Ubuntu
openEuler
Fedora
www-client/firefox
firefox (Ubuntu package)
firefox
firefox-debuginfo
firefox-debugsource

Install updates from vendor's website.

Mozilla Firefox - update to 124.0.1
www-client/firefox - update to 104
firefox (Ubuntu package) - addressed in versions 124.0.1+build1-0ubuntu0.20.04.1, 124.0.2+build1-0ubuntu0.20.04.1
firefox - addressed in versions 124.0.1-1.fc39, 124.0.1-1.fc40
firefox - update to 128.8.0-1
firefox-debuginfo - update to 128.8.0-1
firefox-debugsource - update to 128.8.0-1

• Exploit #12143 - CVE-2024-29943 (November 28, 2025)
• Exploit #10156 - CVE-2024-29943 (July 5, 2024)

• https://www.mozilla.org/en-US/security/advisories/mfsa2024-15/
• https://www.zerodayinitiative.com/advisories/ZDI-24-664/

• Multiple vulnerabilities in Mozilla Firefox and Firefox ESR
• Ubuntu update for firefox
• Fedora 40 update for firefox
• Fedora 39 update for firefox
• Ubuntu update for firefox
• Gentoo update for Mozilla Firefox
• openEuler 22.03 LTS SP4 update for firefox
• openEuler 22.03 LTS SP3 update for firefox