CVE-2026-23270

Published: March 19, 2026Last modified: April 9, 2026

Description

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/[email protected]/

Severity score breakdown

Status

References

• https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189
• https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6
• https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e
• https://git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828
• https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4
• https://git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1