CVE-2026-64530

Critical

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle tcf_classify() can return TC_ACT_CONSUMED while the skb is held by the defragmentation engine (e.g. act_ct on out-of-order fragments). When that happens the skb is no longer owned by the caller and must not be touched again. tcf_qevent_handle() did not handle TC_ACT_CONSUMED: it fell through the switch and returned the skb to the caller as if classification had passed. The only qdisc that wires up qevents today is RED, via three call sites (qe_mark on RED_PROB_MARK/HARD_MARK, qe_early_drop on congestion_drop) red_enqueue() was continuing to operate on an skb it no longer owns in this case -- enqueueing it, dropping it, or updating statistics. Resulting in a UAF. tc qdisc add dev eth0 root handle 1: red ... qevent early_drop block 10 tc filter add block 10 ... action ct (with ct defrag enabled and traffic that produces out-of-order fragments, e.g. a fragmented UDP stream) Handle TC_ACT_CONSUMED in tcf_qevent_handle() the same way the ingress and egress fast paths do: treat it as stolen and return NULL without touching the skb. Unlike the TC_ACT_STOLEN case, the skb must not be dropped/freed here, as it is no longer owned by us.

Package Linux Kernel
Published 2026-07-26
Last modified 2026-07-27
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

9.8

out of 10
Critical
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected versions

Linux kernel versions 5.15.148, 6.1.75, 6.6.14, 6.7.2, 6.8 and later are affected. Fixed in 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5, 7.2-rc1 and their respective stable series.

Affected from
≥ 5.15.148 ≥ 6.1.75 ≥ 6.6.14 ≥ 6.7.2 ≥ 6.8
Fixed in
✓ 5.15.212 5.15.x ✓ 6.1.178 6.1.x ✓ 6.6.145 6.6.x ✓ 6.12.97 6.12.x ✓ 6.18.40 6.18.x ✓ 7.1.5 7.1.x ✓ 7.2-rc1

References

7 total
Showing 5 of 7 references View all on NVD

Frequently asked questions

  • What is CVE-2026-64530?

    CVE-2026-64530 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 5.15.148 onward and has been patched in 5.15.212, 6.1.178, 6.6.145 and others. CVE-2026-64530 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-64530?

    CVE-2026-64530 has a CVSS score of 9.8 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H .

  • Is there a patch available for CVE-2026-64530?

    Yes. CVE-2026-64530 has been patched. Fixed versions include 5.15.212, 6.1.178, 6.6.145 and others. If you are running Linux kernel 5.15.148 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-64530 actively exploited?

    No. CVE-2026-64530 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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