CVE-2026-40686
mediumIn 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 d…
Vendor / product: Exim — exim
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
5.3
5.3 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-04-30 22:16
Modified: 2026-11-11 21:10
NVD status: Analyzed
Last synced 5 hours ago
Verified against the source API 2026-11-11 21:11 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
exim / exim <4.99.2
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
Patch / mitigation: https://code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efc
References
- https://code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efc cve@mitre.org
- https://exim.org/static/doc/security/CVE-2026-40686.txt cve@mitre.org
- https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.assessment cve@mitre.org
- https://www.openwall.com/lists/oss-security/2026/04/30/21 cve@mitre.org
Data sources
NVD CVE API 2.0 — fetched 2026-11-11 21:11 UTC · record ↗