CVE-2026-40686

LOW

Exim < 4.99.2 - Out-of-bounds Read via Malformed UTF-8 Header Data

Title source: llm
STIX 2.1

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.

References (5)

Core 5

Scores

CVSS v3 3.7
EPSS 0.0025
EPSS Percentile 15.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-125
Status published
Products (2)
Exim/Exim < 4.99.2
exim/exim < 4.99.2
Published Apr 30, 2026
Tracked Since May 01, 2026