CVE-2026-23270

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Source
https://cve.org/CVERecord?id=CVE-2026-23270
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23270.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-23270
Downstream
Related
Published
2026-03-18T17:54:43.803Z
Modified
2026-05-15T04:14:26.708298874Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks
Details

In the Linux kernel, the following vulnerability has been resolved:

net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks

As Paolo said earlier [1]:

"Since the blamed commit below, classify can return TCACTCONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet."

actct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TCACTCONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing actct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact).

[1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23270.json"
}
References

Affected packages

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
5.15.203
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.167
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.130
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.77
Type
ECOSYSTEM
Events
Introduced
6.8.0
Fixed
6.18.18
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.19.8

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23270.json"