Quick answers
- Is CVE-2026-74989 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-74989 being exploited in the wild.
- How severe is CVE-2026-74989?
- Critical severity, with a CVSS score of 9.8, published 18 August 2026.
- Which products and versions are affected?
- Mozilla Thunderbird 153.
- Is there a fix for CVE-2026-74989?
- A patch was published on 2026-08: Fixed in Thunderbird 154 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-74989 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-74989?
- Check whether you run Mozilla Firefox or 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.
Technical details
Thunderbird 153 contained multiple memory corruption and security-relevant defects discovered during internal review. The vulnerabilities affect the Thunderbird email client itself and were fixed in version 154. While the specific attack vectors are not detailed in available documentation, memory corruption bugs typically allow remote code execution when triggered through malicious email content or attachments. No evidence of active exploitation in the wild has been reported, but the CVSS 9.8 score indicates high severity. Patches are available in Thunderbird 154 and later.
Affected products
- Mozilla Thunderbird 153
Timeline
- 2026-08-18: disclosed
- 2026-08: patched: Fixed in Thunderbird 154