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ytnef vulnerability

ytnef through 2.1.2 contains a heap out-of-bounds read vulnerability in DecompressRTF() in lib/ytnef.c that never validates uncompressedSize for uncompressed RTF streams. Attackers can supply a crafted winmail.dat TNEF attachment with a malicious PT_BINARY MAPI property to crash ytnefprint or libytnef callers and leak adjacent heap memory.

Published 15 Oct 2026Updated 21 Oct 20265 sources
CVSS 6.9
Overview Sources History

What happened

ytnef through 2.1.2 contains a heap out-of-bounds read vulnerability in DecompressRTF() in lib/ytnef.c that never validates uncompressedSize for uncompressed RTF streams. Attackers can supply a crafted winmail.dat TNEF attachment with a malicious PT_BINARY MAPI property to crash ytnefprint or libytnef callers and leak adjacent heap memory.

Affected versions

ytnef: 0 through 2.1.2 (semver) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

No public PoC reference has passed the current publication threshold.

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