Low severity3.7NVD Advisory· Published Apr 30, 2026· Updated May 1, 2026

CVE-2026-40686

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.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected products

Exim/Exim2 versions
cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*range: <4.99.2
- (no CPE)range: <4.99.2

Patches

Vulnerability mechanics

References

code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efcnvdPatch
exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.assessmentnvdVendor Advisory
www.openwall.com/lists/oss-security/2026/04/30/21nvdMailing ListThird Party Advisory
exim.org/static/doc/security/CVE-2026-40686.txtnvdBroken Link

News mentions

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The Hacker News · May 4, 2026

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