Vulnerability Description
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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux Kernel | >= 6.12, < 6.12.20 |
Related Weaknesses (CWE)
References
- https://git.kernel.org/stable/c/1063ae07383c0ddc5bcce170260c143825846b03Patch
- https://git.kernel.org/stable/c/9e79fdabd52cfce1a021640a81256878a2c516a2Patch
- https://git.kernel.org/stable/c/d91bfc64a4886102746e74d2c6f3a61e9a77fd7dPatch
FAQ
What is CVE-2025-21958?
CVE-2025-21958 is a vulnerability with a CVSS score of 4.7 (MEDIUM). 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...
How severe is CVE-2025-21958?
CVE-2025-21958 has been rated MEDIUM with a CVSS base score of 4.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-21958?
Check the references section above for vendor advisories and patch information. Affected products include: Linux Linux Kernel.