CVE-2026-40687

Publication date 29 April 2026

Last updated 26 June 2026

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
exim4	26.04 LTS resolute	Fixed 4.99.1-1ubuntu1.1
	25.10 questing	Fixed 4.98.2-1ubuntu2.1
	24.04 LTS noble	Fixed 4.97-4ubuntu4.4
	22.04 LTS jammy	Fixed 4.95-4ubuntu2.7
	20.04 LTS focal	Fixed 4.93-13ubuntu1.12+esm1
	18.04 LTS bionic	Ignored changes too intrusive
	16.04 LTS xenial	Ignored end of ESM support, was needs-triage
	14.04 LTS trusty	Ignored changes too intrusive

Get expanded security coverage with Ubuntu Pro

Reduce your average CVE exposure time from 98 days to 1 day with expanded CVE patching, ten-years security maintenance and optional support for the full stack of open-source applications. Free for personal use.

Get Ubuntu Pro 30-day free trial

Notes

mrmajumder

Bionic and below require f3ebb786e451da973560f1c9d8cdb151d25108b5 which introduces over 3000 LoC

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
exim4	Upstream: ecf4e26

Severity score breakdown

CVSS version: CVSS v3.0

Base score 4.8 · Medium

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	Low
Integrity impact	None
Availability impact	Low

Scores

Parameter	Value
Base score	4.8 · Medium
Exploitability score	-
Impact score	-

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

References

Related Ubuntu Security Notices (USN)

USN-8228-1
Exim vulnerabilities
4 May 2026

USN-8382-1
Exim vulnerabilities
3 June 2026