CVE-2026-40684

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Summary

CVECVE-2026-40684
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-30 22:16:25 UTC
Updated2026-05-01 02:16:02 UTC
DescriptionIn Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance when malformed DNS data is present in PTR records. This is caused by a dn_expand oddity in octal printing.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from [email protected]

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

Problem Types: CWE-684 | CWE-684 CWE-684 Incorrect Provision of Specified Functionality

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

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

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

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
code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81 [email protected] code.exim.org
exim.org/static/doc/security/CVE-2026-40684.txt [email protected] exim.org
exim.org/static/doc/security/cve-2026-04.1/CVE2026-40684.assessment [email protected] exim.org
exim.org/static/doc/security/CVE-2025-40684.txt MITRE exim.org
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