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.
History

Fri, 01 May 2026 18:30:00 +0000

Type Values Removed Values Added
References

Fri, 01 May 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 01 May 2026 05:45:00 +0000

Type Values Removed Values Added
Title Denial of Service via malformed DNS PTR records exploits dn_expand bug in Exim on musl systems

Fri, 01 May 2026 02:30:00 +0000

Type Values Removed Values Added
References

Fri, 01 May 2026 02:00:00 +0000

Type Values Removed Values Added
References

Thu, 30 Apr 2026 21:45:00 +0000

Type Values Removed Values Added
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.
First Time appeared Exim
Exim exim
Weaknesses CWE-684
CPEs cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*
Vendors & Products Exim
Exim exim
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published: 2026-04-30T00:00:00.000Z

Updated: 2026-05-01T17:22:32.062Z

Reserved: 2026-04-14T00:00:00.000Z

Link: CVE-2026-40684

cve-icon Vulnrichment

Updated: 2026-05-01T17:22:32.062Z

cve-icon NVD

Status : Modified

Published: 2026-04-30T22:16:25.477

Modified: 2026-05-01T18:16:15.343

Link: CVE-2026-40684

cve-icon Redhat

No data.