Quick answers
- Is CVE-2026-84141 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-84141 being exploited in the wild.
- How severe is CVE-2026-84141?
- Critical severity, with a CVSS score of 9.8, published 1 September 2026.
- Which products and versions are affected?
- Mozilla Firefox before 155; Mozilla Firefox ESR before 153.2; Mozilla Thunderbird before 155; Mozilla Thunderbird ESR before 153.2.
- Is there a fix for CVE-2026-84141?
- A patch was published on 2026-09-01: Fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-84141 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-84141?
- Check whether you run Mozilla Firefox, Mozilla Firefox ESR, Mozilla Thunderbird or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
This is an integer overflow vulnerability in the Graphics: ImageLib component of Firefox. The vulnerability arises from improper bounds checking when processing image data, allowing an attacker to trigger an integer overflow condition. The attack requires the user to view a malicious image file in the browser. An attacker can exploit this to cause denial of service (crash) or potentially achieve remote code execution. The vulnerability has been patched in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
Affected products
- Mozilla Firefox before 155
- Mozilla Firefox ESR before 153.2
- Mozilla Thunderbird before 155
- Mozilla Thunderbird ESR before 153.2
Timeline
- 2026-09-01: disclosed: CVE-2026-84141 publicly disclosed
- 2026-09-01: patched: Fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2