CVE-2026-40685CWE-684

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…

Medium · published April 30, 2026

CVSS v3.1
6.5
EPSS
1%
Percentile
46.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
CVSS v4.0
Not supplied
EPSS
0.00575 · 46.7th percentile
Weakness
CWE-684 · Incorrect Provision of Specified Functionality
Published
2026-04-30T00:00Z
EPSS history
Timeline
  • 30 APR 00:00Z
    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…
    cvelistv5