Out-of-bounds Write Affecting exim4 package, versions <4.98.2-1ubuntu2.1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.1% (27th percentile)

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  • Snyk IDSNYK-UBUNTU2510-EXIM4-16338152
  • published4 May 2026
  • disclosed30 Apr 2026

Introduced: 30 Apr 2026

NewCVE-2026-40685  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Ubuntu:25.10 exim4 to version 4.98.2-1ubuntu2.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream exim4 package and not the exim4 package as distributed by Ubuntu. See How to fix? for Ubuntu:25.10 relevant fixed versions and status.

In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \ skipping.

CVSS Base Scores

version 3.1