CVE-2026-40685CRITICAL 9.8EPSS p23.7%

CVE-2026-40685CVE-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.

Scoring

CVSS 3.19.8 (CRITICAL)
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS0.32% probability of exploitation · percentile 23.7% · 2026-06-19T12:03:05Z
Published2026-04-30
Last modified2026-05-01

Underlying weaknesses· 2

CWE-684CWE-787

References

  1. https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57
  2. https://exim.org/static/doc/security/CVE-2026-40685.txt
  3. https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessment
  4. https://www.openwall.com/lists/oss-security/2026/04/30/21

2

TypeTargetConfidenceTier
WeaknessIncorrect Provision of Specified Functionalitycwe-6840%live
WeaknessOut-of-bounds Writecwe-7870%live

Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.

CVE
CVE-2025-67896
CVE
CVE-2026-40687
CVE
CVE-2026-48840
CVE
Exim Out-of-bounds Write Vulnerability
CVE
Exim Buffer Overflow Vulnerability
CVE
CVE-2026-45185
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.