Is CVE-2026-103678 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-103678 being exploited in the wild.

How severe is CVE-2026-103678?

Medium severity, with a CVSS score of 5.4, published 1 October 2026.

Is there a fix for CVE-2026-103678?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-103678 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2026-103678?

Check whether you run Tnef Project Tnef or Tnef. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-103678: tnef heap out-of-bounds read in RTF data parsing

CVE-2026-103678 · Severity: medium · CVSS 5.4 · Published 2026-10-01

tnef is a utility that extracts attachments and data from email messages. A flaw in how it processes Rich Text Format (RTF) data allows an attacker to craft a malicious email file that causes the application to read beyond allocated memory. This can crash the application, deny service to users, or leak sensitive data from memory into extracted files.

Technologies: Tnef Project Tnef. Vendors: Tnef Project.

Quick answers

Is CVE-2026-103678 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-103678 being exploited in the wild.
How severe is CVE-2026-103678?: Medium severity, with a CVSS score of 5.4, published 1 October 2026.
Which products and versions are affected?: tnef.
Is there a fix for CVE-2026-103678?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-103678 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-103678?: Check whether you run Tnef Project Tnef or Tnef. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is a CWE-125 out-of-bounds read in the get_rtf_data_from_buf() function, triggered when processing specially crafted uncompressed RTF data within MAPI values. An attacker must provide a malicious file as input; no authentication or network access is required. The flaw can result in denial of service (crash) or information disclosure (memory leakage into output files).

Affected products

tnef

Timeline

2026-10-01: disclosed

References

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