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.
Affected products
exim: exim
References4
- exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assess… Vendor Advisory
- code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c8703799… Patch
- exim.org/static/doc/security/CVE-2026-40687.txt Broken Link
- www.openwall.com/lists/oss-security/2026/04/30/21 Mailing ListThird Party Advisory
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H - EPSS — exploit probability
- 0% percentile: 32 · as of 13 November 2026
- CWE
- CWE-909
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