CVE-2026-40686
5.3
MEDIUM
CVSS 3.1
EPSS 0.11%
Description
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.
How to fix CVE-2026-40686
No fixed version has been published yet. Mitigate by removing the affected package or applying upstream guidance from the references below.
- Debian/exim4—no fix listed
Is CVE-2026-40686 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |