CVE-2026-103678 Tnef: heap out-of-bounds read in get_rtf_data_from_buf() via uncompressed rtf mapi value

Medium 5.4 Published 1 Oct 2026 Updated 1 Oct 2026

An attacker can cause a crash or leak memory by providing a crafted file with uncompressed RTF data to the TNEF library.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2026-103678?

CVE-2026-103678 is a medium-severity memory corruption vulnerability in tnef_project:tnef, published on 1 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

A flaw was found in tnef. An attacker can exploit this vulnerability by providing a specially crafted file containing uncompressed Rich Text Format (RTF) data. Because the application fails to properly validate input buffer boundaries before copying data in get_rtf_data_from_buf(), reading beyond the allocated memory occurs. This flaw can cause the application to crash, leading to a Denial of Service (DoS), or leak sensitive memory contents into extracted output files.

Weakness: CWE-125

Which versions are affected by CVE-2026-103678?

It affects 1 product.

Products include Tnef Project Tnef.

How do I fix CVE-2026-103678?

No fix has been published for CVE-2026-103678 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-103678 being exploited?

There is no known exploitation of CVE-2026-103678 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-103678, GHSA-8r4j-263j-fh85, UBUNTU-CVE-2026-103678.