High 7.8Published Mar 18, 2026

CVE-2026-23270net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks

Updated under an hour ago (Oct 28, 2026, 1:40 AM ET)

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Exploited in the last 30 days

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 TC_ACT_CONSUMED 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." act_ct 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 TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct 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/

CVSS: 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 172ba7d46c202e679f3ccb10264c67416aaeb1c4 before bc4e5bb529823a09f02dbe96169de679a9db26e0; from 0b5b831122fc3789fff75be433ba3e4dd7b779d4 before fb3c380a54e33d1fd272cc342faa906d787d7ef1; 73f7da5fd124f2cda9161e2e46114915e6e82e97 builds before 5a110ddcc99bda77a28598b3555fe009eaab3828; from 3f14b377d01d8357eba032b4cabc8c1149b458b6 before 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e; from 3f14b377d01d8357eba032b4cabc8c1149b458b6 before 380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6; from 3f14b377d01d8357eba032b4cabc8c1149b458b6 before 9deda0fcda5c1f388c5e279541850b71a2ccfcf4; from 3f14b377d01d8357eba032b4cabc8c1149b458b6 before 11cb63b0d1a0685e0831ae3c77223e002ef18189; f5346df0591d10bc948761ca854b1fae6d2ef441; and 4 more ranges	CNA record
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 5.15.148 before 5.15.203; from 6.1.75 before 6.1.167; from 6.6.14 before 6.6.130; from 6.7.2 before 6.8; from 6.8 before 6.12.77; from 6.13 before 6.18.18; from 6.19 before 6.19.8; 7.0; and 1 more ranges	NVD

References

References

https://git.kernel.org/stable/c/bc4e5bb529823a09f02dbe96169de679a9db26e0	patch
https://git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1	patch
https://git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828	patch
https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e	patch
https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6	patch
https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4	patch
https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
https://cert-portal.siemens.com/productcert/html/ssa-457936.html
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.