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VulnerabilityPublished Updated

CVE-2026-68338: Linux kernel · net/packet: avoid fanout hook re-registration after unregister

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in c820f4b7f2fa38f8769db0d0cefdd94e2721504d : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in c820f4b7f2fa38f8769db0d0cefdd94e2721504d, acb40ebfa5c4d62f84339fcbf713f2a9fd033a71, a885387dae7986a55bae5c77a15bdd447f64e9b9 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < c820f4b7f2fa38f8769db0d0cefdd94e2721504d
Fixed in
  • c820f4b7f2fa38f8769db0d0cefdd94e2721504d
LinuxLinuxAffected
  • ≥ dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < acb40ebfa5c4d62f84339fcbf713f2a9fd033a71
Fixed in
  • acb40ebfa5c4d62f84339fcbf713f2a9fd033a71
LinuxLinuxAffected
  • ≥ dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < a885387dae7986a55bae5c77a15bdd447f64e9b9
Fixed in
  • a885387dae7986a55bae5c77a15bdd447f64e9b9
LinuxLinuxAffected
  • ≥ dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 4628efbdc7affd094181f5263e65c1062e31f15f
Fixed in
  • 4628efbdc7affd094181f5263e65c1062e31f15f
LinuxLinuxAffected
  • ≥ dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 80ec024d53a05c60ad1d08968dcf745f10c1665c
Fixed in
  • 80ec024d53a05c60ad1d08968dcf745f10c1665c
LinuxLinuxAffected
  • ≥ dc99f600698dcac69b8f56dda9a8a00d645c5ffc, < 50aff80475abd3533eef4320477037e6fcc6b56e
Fixed in
  • 50aff80475abd3533eef4320477037e6fcc6b56e

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.

References

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