CVE-2021-39921

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-11-19 · updated 2026-06-17
Weakness: CWE-476

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

Affected products

Debian Linux: 9.0
Fedoraproject Fedora: 34, 35
Wireshark Foundation Wireshark: from 3.2.0 through 3.2.17; from 3.4.0 through 3.4.9

References

https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39921.json
https://gitlab.com/wireshark/wireshark/-/issues/17703
https://lists.debian.org/debian-lts-announce/2021/12/msg00015.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A6AJFIYIHS3TYDD2EBYBJ5KKE52X34BJ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YEWTIRMC2MFQBZ2O5M4CJHJM4JPBHLXH/
https://security.gentoo.org/glsa/202210-04
https://www.debian.org/security/2021/dsa-5019
https://www.wireshark.org/security/wnpa-sec-2021-14.html
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39921.json
https://gitlab.com/wireshark/wireshark/-/issues/17703
https://lists.debian.org/debian-lts-announce/2021/12/msg00015.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A6AJFIYIHS3TYDD2EBYBJ5KKE52X34BJ/

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