CVE-2026-40687 PUBLISHED

Assigner: mitre
Reserved: 14.04.2026 Published: 30.04.2026 Updated: 01.05.2026

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.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
CVSS Score: 4.8

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	Low
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	Exim
Product	Exim
Versions	Default: unaffected affected from 0 to 4.99.2 (excl.)

References

https://www.openwall.com/lists/oss-security/2026/04/30/21
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assessment
https://code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c87037990199f505
https://exim.org/static/doc/security/CVE-2026-40687.txt

Problem Types

CWE-909 Missing Initialization of Resource CWE