CVE-2026-40684

April 30, 2026, 10:16 p.m.

5.9
Medium

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.

Product(s) Impacted

Vendor Product Versions
Exim
  • Exim
  • <4.99.2

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-684
Incorrect Provision of Specified Functionality
The code does not function according to its published specifications, potentially leading to incorrect usage.

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
a exim exim <4.99.2 / / / / / / /

References

https://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81
https://exim.org/static/doc/security/CVE-2025-40684.txt
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40684.assessment
https://www.openwall.com/lists/oss-security/2026/04/30/21

Tags

[email protected]
CWE-684
2026-04-30
CVE-2026-40684

CVSS Score

5.9 / 10

CVSS Data - 3.1

  • Attack Vector: NETWORK
  • Attack Complexity: HIGH
  • Privileges Required: NONE
  • Scope: UNCHANGED
  • Confidentiality Impact: NONE
  • Integrity Impact: NONE
  • Availability Impact: HIGH

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

    View Vector String

Timeline

Published: April 30, 2026, 10:16 p.m.
Last Modified: April 30, 2026, 10:16 p.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

[email protected]

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.