CVE-2021-20177

low
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
2.5

Description

A flaw was found in the Linux kernel's implementation of string matching within a packet. A privileged user (with root or CAP_NET_ADMIN) when inserting iptables rules could insert a rule which can panic the system. Kernel before kernel 5.5-rc1 is affected.

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-2021-20177

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-20177.html

OS impact

OSVersionStatusFixed in
arch archfixed5.4.81-1
suse slesaffected
debian debianbookwormfixed5.5.13-1
debian debianbullseyefixed5.5.13-1
debian debianforkyfixed5.5.13-1
debian debiansidfixed5.5.13-1
debian debiantrixiefixed5.5.13-1

References

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