Vulnerability 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.
CVSS Score
6.5
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Exim | Exim | < 4.99.2 |
Related Weaknesses (CWE)
References
- https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57Patch
- https://exim.org/static/doc/security/CVE-2026-40685.txtBroken Link
- https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessmentVendor Advisory
- https://www.openwall.com/lists/oss-security/2026/04/30/21Mailing ListThird Party Advisory
FAQ
What is CVE-2026-40685?
CVE-2026-40685 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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 ...
How severe is CVE-2026-40685?
CVE-2026-40685 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-40685?
Check the references section above for vendor advisories and patch information. Affected products include: Exim Exim.