CVE-2026-40686

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Summary

CVECVE-2026-40686
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-30 22:16:25 UTC
Updated2026-05-01 02:16:04 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 3.7 LOW from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Problem Types: CWE-125 | CWE-125 CWE-125 Out-of-bounds Read

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1CNACVSS3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Exim Exim affected 4.99.2 semver Not specified

References

ReferenceSourceLinkTags
www.openwall.com/lists/oss-security/2026/04/30/21 [email protected] www.openwall.com
exim.org/static/doc/security/CVE-2026-40686.txt [email protected] exim.org
code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efc [email protected] code.exim.org
exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.assessment [email protected] exim.org
exim.org/static/doc/security/CVE-2025-40686.txt MITRE exim.org
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