Vulnerability DatabaseCVE-2026-40684
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CVE-2026-40684
Published:April 30, 2026
Updated:August 06, 2026
In 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.
Affected Packages
https://github.com/Exim/exim.git (GITHUB):
Affected version(s) >=exim-4_50 <exim-4.99.2
Fix Suggestion:
Update to version exim-4.99.2
Related Resources (6)
https://exim.org/static/doc/security/CVE-2025-40684.txt
https://www.openwall.com/lists/oss-security/2026/04/30/21
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40684.assessment
https://exim.org/static/doc/security/CVE-2026-40684.txt
https://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81
http://www.openwall.com/lists/oss-security/2026/05/01/11
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CVSS v4
Base Score:
8.2
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.9
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Incorrect Provision of Specified Functionality
CWE-684
EPSS
Base Score:
0.36