CVE-2026-40686: In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing…
CVE-2026-40686 · Severity: low · CVSS 3.7 · Published 2026-04-30
In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.
No. Junglewise Threat Intelligence has no report of CVE-2026-40686 being exploited in the wild.
How severe is CVE-2026-40686?
Low severity, with a CVSS score of 3.7, published 30 April 2026.
Which products and versions are affected?
Exim. The advisory does not name versions.
Is there a fix for CVE-2026-40686?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-40686?
Check whether you run Exim. 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.