CVE-2026-40685
9.8
CRITICAL
CVSS 3.1
EPSS 0.13%
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.
How to fix CVE-2026-40685
No fixed version has been published yet. Mitigate by removing the affected package or applying upstream guidance from the references below.
- Debian/exim4—no fix listed
Is CVE-2026-40685 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | CRITICAL9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |