CVE Catalog

CVE-2025-21958

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.14%

4th percentile - higher than 4% of all known CVEs

Summary

In the Linux kernel, the openvswitch module reverted a commit that introduced per-action label counting in conntrack. The new implementation caused a warning when trying to allocate the labels_ext extension for a confirmed conntrack entry, which occurred when the entry was created before OVS incremented the labels_used counter.

Risk Assessment

This could lead to kernel warnings and potentially incorrect conntrack behavior, affecting connection processing in Open vSwitch.

Recommendation

Update the Linux kernel to a version containing the fix for CVE-2025-21958 (revert).

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: Revert "openvswitch: switch to per-action label counting in conntrack" Currently, ovs_ct_set_labels() is only called for confirmed conntrack entries (ct) within ovs_ct_commit(). However, if the conntrack entry does not have the labels_ext extension, attempting to allocate it in ovs_ct_get_conn_labels() for a confirmed entry triggers a warning in nf_ct_ext_add(): WARN_ON(nf_ct_is_confirmed(ct)); This happens when the conntrack entry is created externally before OVS increments net->ct.labels_used. The issue has become more likely since commit fcb1aa5163b1 ("openvswitch: switch to per-action label counting in conntrack"), which changed to use per-action label counting and increment net->ct.labels_used when a flow with ct action is added. Since there’s no straightforward way to fully resolve this issue at the moment, this reverts the commit to avoid breaking existing use cases.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS