CVE-2026-64207 Linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: net/sched: dualpi2: fix GSO backlog accounting When DualPI2 splits a GSO skb into N segments, it propagates N additional packets to its parent before returning NET_XMIT_SUCCESS. The parent then accounts for the original skb once more, leaving its qlen one larger than the number of packets actually queued. With QFQ as the parent, after all real packets are dequeued, QFQ still has a non-zero qlen while its in-service aggregate has no active classes. qfq_choose_next_agg() returns NULL and qfq_dequeue() passes the result to qfq_peek_skb(), causing a NULL pointer dereference. Follow the same pattern used by tbf_segment() and taprio: count only successfully queued segments, propagate the difference between the original skb and those segments, and return NET_XMIT_SUCCESS whenever at least one segment was queued.
Browse Linux security risksQuick answer
Linux should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- < c4b70c1512b8f9f33f23c2c8196dfd1210207681
- < 806586e33891066487db1f002be3d455cda6b516
- < 05ed733b65ab977dd931e7f7ac0f62fdb81205c2
- 6.17
Fixed versions
- 6.18.39
- 7.1.4
- 7.2-rc1
How to fix it
CVE-2026-64207 affects Linux and involves security-control failure. Successful exploitation may affect the confidentiality, integrity, or availability of the affected workflow. Prioritize deployments that process untrusted input, expose the affected feature, or hold sensitive data. Upgrade Linux to 6.18.39, 7.1.4, 7.2-rc1 or a later vendor-supported fixed release.
- Inventory every deployment, device, package, plugin, container, build, and environment that uses Linux.
- Compare the installed version with the recorded affected range: < c4b70c1512b8f9f33f23c2c8196dfd1210207681, < 806586e33891066487db1f002be3d455cda6b516, < 05ed733b65ab977dd931e7f7ac0f62fdb81205c2, 6.17.
- Upgrade Linux to 6.18.39, 7.1.4, 7.2-rc1 or a later vendor-supported fixed release.
- Until patched, reduce public exposure, disable the affected workflow where practical, and allow access only from trusted users and systems.
- Review configuration, roles, tokens, network paths, and exposed endpoints connected to Linux; remove access that is not required.
- Review application, system, proxy, and audit logs for requests and behavior linked to the affected feature and CVE.
- If exploitation is suspected, isolate affected assets, preserve evidence, rotate exposed credentials or keys, restore trusted data, and rebuild compromised systems before returning them to service.
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Verify the fix
- Confirm every affected asset now runs the fixed vendor-supported release or has the documented mitigation for CVE-2026-64207 in place.
- Use a safe regression test to confirm the affected security-control failure path no longer produces the vulnerable behavior.
- Confirm temporary access controls, endpoint restrictions, network blocks, and least-privilege settings remain effective after the update.
- Review post-remediation logs and rerun Fixnx plus the relevant package, dependency, firmware, browser, or product-specific security check.
- Document affected assets, versions, changes, validation evidence, reviewed logs, and any credential rotation, cleanup, or replacement completed.
Related categories
Related security risks
More published guidance from the same primary category.
Trusted references
FAQ
What is affected by CVE-2026-64207?
Linux versions listed as affected should be reviewed: < c4b70c1512b8f9f33f23c2c8196dfd1210207681, < 806586e33891066487db1f002be3d455cda6b516, < 05ed733b65ab977dd931e7f7ac0f62fdb81205c2, 6.17.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.