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.
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.
Published:
2026-07-26
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data.
No data.
No data available yet.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Advisories
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References
History
Sun, 26 Jul 2026 07:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | net/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-07-26T06:28:42.970Z
Reserved: 2026-07-19T15:36:31.794Z
Link: CVE-2026-64530
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.