CVE-2026-40685

MEDIUM

Exim < 4.99.2 - Heap-Based Buffer Overflow via Malformed JSON Header Processing

Title source: llm
STIX 2.1

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.

References (5)

Core 5

Scores

CVSS v3 6.5
EPSS 0.0032
EPSS Percentile 23.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-684 CWE-787
Status published
Products (2)
Exim/Exim < 4.99.2
exim/exim < 4.99.2
Published Apr 30, 2026
Tracked Since May 01, 2026