Medium severity6.5NVD Advisory· Published Apr 30, 2026· Updated May 1, 2026

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.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected products

Exim/Exim2 versions
cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*range: <4.99.2
- (no CPE)range: <4.99.2

Patches

Vulnerability mechanics

References

code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57nvdPatch
exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessmentnvdVendor Advisory
www.openwall.com/lists/oss-security/2026/04/30/21nvdMailing ListThird Party Advisory
exim.org/static/doc/security/CVE-2026-40685.txtnvdBroken Link

News mentions

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The Hacker News · May 4, 2026

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