HIGH

CVE-2021-3404

CVSS v3

7.8

HIGH

EPSS Score

1.9 %

exploit probability, as of 2026-10-19

CISA KEV

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

CVE-2021-3404 Red Hat Product Security
ytnef: heap-based buffer overflow in SwapWord function in lib/ytnef.c via crafted file

Full record on 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.

Technical details

Published: 2021-03-04

Frequently asked questions

What is CVE-2021-3404?

Is CVE-2021-3404 actively exploited?

Active exploitation of CVE-2021-3404 has not been confirmed. Its EPSS score was 1.9% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-3404?

CVE-2021-3404 has a CVSS v3 base score of 7.8 (HIGH severity).

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