CVE-2026-40687

EUVD-2026-26445
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
mitreCNA
4.8 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: 16.05%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
eximexim
𝑥
< 4.99.2
CNA
Debian logo
Debian Releases
Debian Product
Codename
exim4
bookworm
vulnerable
bookworm (security)
vulnerable
bullseye
vulnerable
bullseye (security)
vulnerable
forky
vulnerable
sid
4.99.2-1
fixed
trixie
vulnerable
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
exim4
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
questing
needs-triage
resolute
needs-triage
trusty
needs-triage
xenial
needs-triage
Common Weakness Enumeration
References
https://code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c87037990199f505
https://exim.org/static/doc/security/CVE-2026-40687.txt
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assessment
https://www.openwall.com/lists/oss-security/2026/04/30/21