Vulnerability in Exim
CVE-2026-40687
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L.
EPSS exploit prediction
EPSS: 0.007 (51.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.007 · change: +0.003
Affected products
- Exim — versions 0
Weakness classification (CWE)
References
- www.openwall.com/lists/oss-security/2026/04/30/21 (Mailing List, Third Party Advisory)
- exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assessment (Vendor Advisory)
- code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c87037990199f505 (Patch)
- exim.org/static/doc/security/CVE-2026-40687.txt (Broken Link)
Frequently asked questions
- What is CVE-2026-40687?
- CVE-2026-40687 is a medium-severity vulnerability in Exim, classified under CWE-909. CVSS score: 4.8/10. Published 2026-04-30.
- How severe is CVE-2026-40687?
- Medium severity. CVSS v3 base score is 4.8 out of 10.