- Vulnerability/
- CVE-2025-21958
CVE-2025-21958: Revert "openvswitch: switch to per-action label counting in conntrack"
First published: Tue Apr 01 2025(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Open vSwitch |
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Reference Links
Frequently Asked Questions
What is the severity of CVE-2025-21958?
CVE-2025-21958 is classified as a high-severity vulnerability affecting the Linux kernel and Open vSwitch.
How do I fix CVE-2025-21958?
To fix CVE-2025-21958, update your Linux kernel or Open vSwitch software to the latest patched version.
Which versions of Linux kernel are affected by CVE-2025-21958?
CVE-2025-21958 affects specific versions of the Linux kernel that implemented the vulnerable conntrack functionality.
What kind of systems are impacted by CVE-2025-21958?
Systems running vulnerable versions of the Linux kernel or Open vSwitch are at risk due to CVE-2025-21958.
What is the nature of the vulnerability in CVE-2025-21958?
CVE-2025-21958 is a vulnerability related to improper label counting in connection tracking within the Linux kernel.
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