CVE-2026-40685

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.

PUBLISHED Reserved 2026-04-14 | Published 2026-04-30 | Updated 2026-05-01 | Assigner mitre

Problem types

CWE-684 Incorrect Provision of Specified Functionality

Product status

References

www.openwall.com/lists/oss-security/2026/04/30/21

exim.org/.../security/cve-2026-04.1/CVE2026-40685.assessment

code.exim.org/...it/9fdc057e71b87c87a0d3d2288b2810a0efaaba57

exim.org/static/doc/security/CVE-2026-40685.txt

cve.org (CVE-2026-40685)

nvd.nist.gov (CVE-2026-40685)

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