CVE-2026-40685

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 v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57	Patch
https://exim.org/static/doc/security/CVE-2026-40685.txt	Broken Link
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessment	Vendor Advisory
https://www.openwall.com/lists/oss-security/2026/04/30/21	Mailing List Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-04-30 22:16

Updated : 2026-06-17 10:45

NVD link : CVE-2026-40685

Mitre link : CVE-2026-40685

CVE.ORG link : CVE-2026-40685

JSON object : View

Products Affected

exim

exim

CWE

CWE-684

Incorrect Provision of Specified Functionality

CWE-787

Out-of-bounds Write

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