CVE-2025-21958

MEDIUMNVD 4.74.7—
EchelonGraph scoreMEDIUM confidence

Score 4.7 from GitHub Security Advisory published 2025-04-01. NVD baseline CVSS 4.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
4.7
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.7Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
4.7
EG Score
4.7(medium)
EG Risk
26(Track)
EG Risk 26/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity47% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
3.2%
KEV
Not listed

Published

April 1, 2025

Last Modified

October 31, 2025

References (3)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:17 UTCEPSS rescore
  2. 2026-07-23 02:50 UTCEG score recompute
  3. 2026-07-22 14:07 UTCEPSS rescore
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  58. 2026-05-30 08:23 UTCEG score recompute
  59. 2026-05-30 08:23 UTCGHSA enrichment
  60. 2026-05-30 07:59 UTCOSV refresh
  61. 2026-05-29 13:44 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2025-21958?
CVE-2025-21958 is a medium vulnerability published on April 1, 2025. In the Linux kernel, the following vulnerability has been resolved: Revert "openvswitch: switch to per-action label counting in conntrack" Currently, ovsctset_labels() is only called for confirmed conntrack entries (ct) within ovsctcommit(). However, if the conntrack entry does not have the…
When was CVE-2025-21958 disclosed?
CVE-2025-21958 was first published in the National Vulnerability Database on April 1, 2025, with the most recent update on October 31, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21958 actively exploited?
CVE-2025-21958 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-21958?
CVE-2025-21958 has a CVSS v3 base score of 4.7 (NVD).
How do I remediate CVE-2025-21958?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21958, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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