CVE-2026-64530: In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle tcf_classify() c...

Description

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

0.17%

7.0th 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	>= 172ba7d46c202e679f3ccb10264c67416aaeb1c4, < 5ed3d6f85991656667059d3fa5a1d683ac58c447; >= 0b5b831122fc3789fff75be433ba3e4dd7b779d4, < f42e8134a3a1074b834a574d404352f867ba994a; >= 73f7da5fd124f2cda9161e2e46114915e6e82e97, < 447d493034a9cf7bf13a2abac86d0573d907ec2f; >= 3f14b377d01d8357eba032b4cabc8c1149b458b6, < e1270e69dcf2c3512c453484178f2e9dc0db3f05; >= 3f14b377d01d8357eba032b4cabc8c1149b458b6, < 2140c2f3f2e7b066e1ae616ede8856cafd8015e9; >= 3f14b377d01d8357eba032b4cabc8c1149b458b6, < e28aedab9488343924d227b5a896faed67ce84d5; >= 3f14b377d01d8357eba032b4cabc8c1149b458b6, < a8a02897f2b479127db261de05cbf0c28b98d159; f5346df0591d10bc948761ca854b1fae6d2ef441; >= 5.15.148, < 5.15.212; >= 6.1.75, < 6.1.178; >= 6.6.14, < 6.6.145; >= 6.7.2, < 6.8
Linux	Linux	6.8

References

Timeline

Published: Jul 26, 2026
Last Modified: Jul 27, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-64530?

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.

How severe is CVE-2026-64530?

CVE-2026-64530 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2026-64530?

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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