Quick answers
- Is CVE-2026-110247 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-110247 being exploited in the wild.
- How severe is CVE-2026-110247?
- Informational severity, published 13 October 2026.
- Which products and versions are affected?
- Mozilla Thunderbird before 158.
- Is there a fix for CVE-2026-110247?
- Yes: fixed in Thunderbird 158. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-110247 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-110247?
- 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
Technical details
An integer overflow in 32-bit size arithmetic within libmime's buffer-growth sites allows a growth guard to fail or cause buffer reallocation to a smaller-than-required size. A subsequent memcpy writes attacker-controlled data across adjacent heap allocations, enabling heap corruption. The vulnerability requires a sufficiently large malicious message to trigger; it was fixed in Thunderbird 158.
Affected products
- Mozilla Thunderbird before 158
Timeline
- 2026-10-13: disclosed