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Vulnerability record · CVE-2021-3404 · published 4 March 2021

CVE-2021-3404: Ytnef project ytnef memory buffer overflow vulnerability

YYtnef Project · Ytnef

In ytnef 1.9.3, the SwapWord function in lib/ytnef.c allows remote attackers to cause a denial-of-service (and potentially code execution) due to a heap buffer overflow which can be triggered via a crafted file.

7.8 CVSS 3.1 High EPSS 1.9% · top 20.6% CWE-119 · Memory buffer overflowCWE-787 · Out-of-bounds write
7.8CVSS 3.1 base score, v2 6.8
1.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

In ytnef 1.9.3, the SwapWord function in lib/ytnef.c allows remote attackers to cause a denial-of-service (and potentially code execution) due to a heap buffer overflow which can be triggered via a crafted file.

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

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=1926965 Issue TrackingThird Party Advisory
https://github.com/Yeraze/ytnef/issues/86 ExploitIssue TrackingThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1926965 Issue TrackingThird Party Advisory
https://github.com/Yeraze/ytnef/issues/86 ExploitIssue TrackingThird Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-3404), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.