CVE-2021-39921

low

Published — · Modified —

CVSS v3

—

CVSS v2

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VIR risk

2.5

Description

NULL pointer exception in the Modbus dissector in Wireshark 3.4.0 to 3.4.9 and 3.2.0 to 3.2.17 allows denial of service via packet injection or crafted capture file

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-39921

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-39921.html

OS impact

OS	Version	Status	Fixed in
arch		fixed	`3.4.10-1`
sles		affected
debian	bookworm	fixed	`3.6.0-1`
debian	bullseye	fixed	`3.4.10-0+deb11u1`
debian	forky	fixed	`3.6.0-1`
debian	sid	fixed	`3.6.0-1`
debian	trixie	fixed	`3.6.0-1`

References

https://www.suse.com/security/cve/CVE-2021-39921.html
https://security-tracker.debian.org/tracker/CVE-2021-39921

Verify integrity in audit chain (admin only). AS-IS.