CVE-2026-68338: Linux Vulnerability (CVSS 7.8)

Description

In the Linux kernel, the following vulnerability has been resolved: net/packet: avoid fanout hook re-registration after unregister packet_set_ring() temporarily detaches a socket from packet delivery while reconfiguring its ring. It records the previous running state, clears po->num, unregisters the protocol hook when needed, drops po->bind_lock, and later restores po->num and re-registers the hook from the saved was_running value. That unlocked window can race with NETDEV_UNREGISTER. The notifier can observe the socket as not running, skip __unregister_prot_hook(), and invalidate the per-socket binding by setting po->ifindex to -1 and clearing po->prot_hook.dev. A one-member fanout group can still retain its shared fanout hook device pointer. When packet_set_ring() resumes, re-registering solely from the stale was_running state can re-add the fanout hook after the device has been unregistered. Treat po->ifindex == -1 as an invalidated binding after reacquiring po->bind_lock. This is distinct from ifindex 0, the normal unbound/wildcard state: ifindex -1 marks an existing device binding that was invalidated when the device was unregistered. Restore po->num as before, but do not re-register the hook if device unregister already detached the socket.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.18%

7.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < acb40ebfa5c4d62f84339fcbf713f2a9fd033a71; >= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < c820f4b7f2fa38f8769db0d0cefdd94e2721504d; >= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 4628efbdc7affd094181f5263e65c1062e31f15f; >= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 80ec024d53a05c60ad1d08968dcf745f10c1665c; >= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 0a052e0808e015e68144a9877e6ef42b952c49fa; >= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 1bc55c29cd85818e9052f17deb287d5a11fb817f; >= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < a885387dae7986a55bae5c77a15bdd447f64e9b9; >= dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 50aff80475abd3533eef4320477037e6fcc6b56e
Linux	Linux	3.1

References

Timeline

Published: Aug 10, 2026
Last Modified: Aug 19, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-68338?

In the Linux kernel, the following vulnerability has been resolved: net/packet: avoid fanout hook re-registration after unregister packet_set_ring() temporarily detaches a socket from packet delivery while reconfiguring its ring. It records the previous running state, clears po->num, unregisters the protocol hook when needed, drops po->bind_lock, and later restores po->num and re-registers the hook from the saved was_running value. That unlocked window can race with NETDEV_UNREGISTER. The notifier can observe the socket as not running, skip __unregister_prot_hook(), and invalidate the per-socket binding by setting po->ifindex to -1 and clearing po->prot_hook.dev. A one-member fanout group can still retain its shared fanout hook device pointer. When packet_set_ring() resumes, re-registering solely from the stale was_running state can re-add the fanout hook after the device has been unregistered. Treat po->ifindex == -1 as an invalidated binding after reacquiring po->bind_lock. This is distinct from ifindex 0, the normal unbound/wildcard state: ifindex -1 marks an existing device binding that was invalidated when the device was unregistered. Restore po->num as before, but do not re-register the hook if device unregister already detached the socket.

How severe is CVE-2026-68338?

CVE-2026-68338 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.

How do I fix CVE-2026-68338?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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