CVE-2026-40684

HIGH EPSS 28.1%
Published Apr 30, 20262mo ago · Modified Jun 17, 20262w ago
7.5 CVSS 3.1
High
Find Similar
Published Apr 30, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

Description

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.

CVSS Details

Base Score
7.5
Exploitability
3.9
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
28.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-684

Affected Products 1

VendorProductVersionRange
eximexim* <4.99.2

References 5

  • openwall.com http://www.openwall.com/lists/oss-security/2026/05/01/11
  • code.exim.org https://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81
    Patch
  • exim.org https://exim.org/static/doc/security/CVE-2026-40684.txt
    Broken Link
  • exim.org https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40684.assessment
    Vendor Advisory
  • openwall.com https://www.openwall.com/lists/oss-security/2026/04/30/21
    Mailing ListThird Party Advisory

Remediation

  • code.exim.org https://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81
    Patch