Vulnerability DatabaseCVE-2026-40685
Mend.io Vulnerability Database
The largest open source vulnerability database
What is a Vulnerability ID?
New vulnerability? Tell us about it!
CVE-2026-40685
Published:April 30, 2026
Updated:May 18, 2026
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.
Affected Packages
https://github.com/Exim/exim.git (GITHUB):
Affected version(s) >=exim-4_50 <exim-4.99.2
Fix Suggestion:
Update to version exim-4.99.2
Related Resources (5)
https://exim.org/static/doc/security/CVE-2025-40685.txt
https://exim.org/static/doc/security/CVE-2026-40685.txt
https://www.openwall.com/lists/oss-security/2026/04/30/21
https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessment
Do you need more information?
Contact Us
CVSS v4
Base Score:
8.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
LOW
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.5
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
HIGH
Weakness Type (CWE)
Out-of-bounds Write
CWE-787
Incorrect Provision of Specified Functionality
CWE-684
EPSS
Base Score:
0.10