Quick answers
- Is CVE-2026-113869 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-113869 being exploited in the wild.
- How severe is CVE-2026-113869?
- Medium severity, with a CVSS score of 5.4, published 20 October 2026.
- Which products and versions are affected?
- Mozilla Thunderbird before 158.0.1.
- Is there a fix for CVE-2026-113869?
- Yes: fixed in Thunderbird 158.0.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-113869 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-113869?
- Check whether you run Mozilla Thunderbird 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: Thunderbird 158.0.1
Technical details
A use-after-free vulnerability in S/MIME message decryption occurs when the message decoder is freed while a security device password prompt is still active. If the message load completes or is cancelled during the prompt, the decoder is freed but subsequently referenced, leading to a crash. Exploitation requires the ability to send a specially crafted S/MIME message and user interaction to trigger the password prompt.
Affected products
- Mozilla Thunderbird before 158.0.1
Timeline
- 2026-10-20: disclosed