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

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Summary

CVECVE-2026-23270
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-18 18:16:26 UTC
Updated2026-04-02 15:16:27 UTC
DescriptionIn 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/[email protected]/

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.000320000 probability, percentile 0.091780000 (date 2026-04-02)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 0b5b831122fc3789fff75be433ba3e4dd7b779d4 fb3c380a54e33d1fd272cc342faa906d787d7ef1 git Not specified
CNA Linux Linux affected 73f7da5fd124f2cda9161e2e46114915e6e82e97 5a110ddcc99bda77a28598b3555fe009eaab3828 git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6 git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 9deda0fcda5c1f388c5e279541850b71a2ccfcf4 git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 11cb63b0d1a0685e0831ae3c77223e002ef18189 git Not specified
CNA Linux Linux affected 172ba7d46c202e679f3ccb10264c67416aaeb1c4 git Not specified
CNA Linux Linux affected f5346df0591d10bc948761ca854b1fae6d2ef441 git Not specified
CNA Linux Linux affected 6.8 Not specified
CNA Linux Linux unaffected 6.8 semver Not specified
CNA Linux Linux unaffected 6.1.167 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.130 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.77 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.18 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.8 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0-rc3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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