CVE-2026-103680

LOW 3.1

Tnef: heap buffer overflow in find_free_number() via numbered-backup suffix generation

CVSS Score

3.1

EPSS Score

0.0%

EPSS Percentile

0th

A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.

CWE	CWE-787
Published	Oct 1, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

References

NVD ↗ CVE.org ↗ EPSS Data ↗

access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-103680 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2544478 github.com: https://github.com/verdammelt/tnef

Credits

Red Hat would like to thank Julien Ahrens (RCE Security GmbH) for reporting this issue.