Quick answers
- Is CVE-2026-109713 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-109713 being exploited in the wild.
- How severe is CVE-2026-109713?
- Medium severity, with a CVSS score of 5.4, published 13 October 2026.
- Which products and versions are affected?
- Mozilla Firefox before 158; Mozilla Firefox ESR before 153.5; Mozilla Thunderbird before 158; Mozilla Thunderbird ESR before 153.5.
- Is there a fix for CVE-2026-109713?
- Yes: fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird ESR 153.5. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-109713 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-109713?
- 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.
How to fix
- Fixed in: Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird ESR 153.5
Technical details
A use-after-free vulnerability exists in the Crash Reporting component of Firefox and Thunderbird. The vulnerability is triggered when memory is accessed after being freed, which can lead to denial of service or potentially arbitrary code execution depending on heap conditions and exploitation sophistication. No evidence of active exploitation in the wild has been reported.
Affected products
- Mozilla Firefox before 158
- Mozilla Firefox ESR before 153.5
- Mozilla Thunderbird before 158
- Mozilla Thunderbird ESR before 153.5
Timeline
- 2026-10-13: disclosed: Vulnerability announced in Mozilla Security Advisory