Out-of-bounds Read in Exim
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 characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during hand…
Vulnerability class: Buffer Overflow
EPSS: 0.001 (28.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Exim — versions 0
Weakness classification (CWE)
References
- cve@mitre.org (Mailing List, Third Party Advisory)
- cve@mitre.org (Vendor Advisory)
- cve@mitre.org (Patch)
- cve@mitre.org (Broken Link)
Frequently asked questions
- What is CVE-2026-40686?
- CVE-2026-40686 is a low-severity vulnerability in Exim, classified under Out-of-bounds Read. CVSS score: 3.7/10. Published 2026-04-30.
- How severe is CVE-2026-40686?
- Low severity. CVSS v3 base score is 3.7 out of 10.