CVE-2026-40685

State: Published
Severity: 6.5 Medium
Published: Apr 30, 2026
Updated: May 1, 2026
Reserved: Apr 14, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H	mitre

Weaknesses

CWE-684 Incorrect Provision of Specified Functionality

Affected Products

Product	Versions
EximExim	before 4.99.2Affected

References

https://www.openwall.com/lists/oss-security/2026/04/30/21
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessment
https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57
https://exim.org/static/doc/security/CVE-2026-40685.txt

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