CVE-2026-40685

CRITICAL EPSS 23.8%
Published Apr 30, 20262mo ago · Modified Jun 17, 20262w ago
9.8 CVSS 3.1
Critical
Find Similar
Published Apr 30, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

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 Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
23.8% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 2

CWE-684
CWE-787 Out-of-bounds Write Memory Safety

Affected Products 1

VendorProductVersionRange
eximexim* <4.99.2

References 4

  • code.exim.org https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57
    Patch
  • exim.org https://exim.org/static/doc/security/CVE-2026-40685.txt
    Broken Link
  • exim.org https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40685.assessment
    Vendor Advisory
  • openwall.com https://www.openwall.com/lists/oss-security/2026/04/30/21
    Mailing ListThird Party Advisory

Remediation

  • code.exim.org https://code.exim.org/exim/exim/commit/9fdc057e71b87c87a0d3d2288b2810a0efaaba57
    Patch