# CVE-2026-40685

## Summary

- **CVE ID:** CVE-2026-40685
- **Severity:** MEDIUM
- **CVSS Score:** 6.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H)
- **CWE:** CWE-684
- **Published:** Apr 30, 2026
- **Last Modified:** May 1, 2026

## 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.

## Affected Products

- Exim — Exim (0)

## References

- [CNA](https://exim.org/static/doc/security/CVE-2025-40685.txt)
- [CNA](https://www.openwall.com/lists/oss-security/2026/04/30/21)
- [CNA](https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessment)
- [CNA](https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57)
- [CNA](https://exim.org/static/doc/security/CVE-2026-40685.txt)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.32%
- **EPSS Percentile:** 24.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._