CVE-2026-40686

MEDIUM EPSS 15.7%
Published Apr 30, 20262mo ago · Modified Jun 17, 20262w ago
5.3 CVSS 3.1
Medium
Find Similar
Published Apr 30, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

Description

In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.

CVSS Details

Base Score
5.3
Exploitability
3.9
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Low
Integrity None
Availability None

Threat Intelligence

EPSS Exploit Probability
15.7% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-125 Out-of-bounds Read Memory Safety

Affected Products 1

VendorProductVersionRange
eximexim* <4.99.2

References 4

  • code.exim.org https://code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efc
    Patch
  • exim.org https://exim.org/static/doc/security/CVE-2026-40686.txt
    Broken Link
  • exim.org https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.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/f2570bde16fb4d4a1242ff363a4c4eecf6372efc
    Patch