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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-103680
StatePUBLISHED
Assignerfedora
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-01 12:17:15 UTC
Updated2026-10-01 15:17:28 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.1 3.1 LOW from [email protected]

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

Problem Types: CWE-787 | CWE-787 Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.1LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
3.1CNACVSS3.1LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

References

ReferenceSourceLinkTags
access.redhat.com/security/cve/CVE-2026-103680 [email protected] access.redhat.com
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
github.com/verdammelt/tnef [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

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

Additional Advisory Data

SourceTimeEvent
CNA2026-09-30T19:37:30.000ZReported to Red Hat.
CNA2026-10-01T00:00:00.000ZMade public.

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