CVE-2026-40687

critical

Description

In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that divulges data from uninitialized heap memory.

References

https://www.openwall.com/lists/oss-security/2026/04/30/21

https://seclists.org/oss-sec/2026/q2/306

https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assessment

https://exim.org/static/doc/security/CVE-2026-40687.txt

https://code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c87037990199f505

Details

Source: Mitre, NVD

Published: 2026-04-30

Updated: 2026-05-01

Risk Information

CVSS v2

Base Score: 9.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:N/A:C

Severity: High

CVSS v3

Base Score: 9.1

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

Severity: Critical

EPSS

EPSS: 0.00052