PT-2026-26130 · Linux · Linux

Published 2026-03-18 · Updated 2026-03-18 · CVE-2026-23270

Mitre

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/[e-mail]/ [2] https://lore.kernel.org/netdev/[e-mail]/

Related Identifiers

CVE-2026-23270

Affected Products

Linux

References · 5

• https://nvd.nist.gov/vuln/detail/CVE-2026-23270 · Security Note
• https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6 · Note
• https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4 · Note
• https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189 · Note
• https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e · Note