Threats Tagged 'cve-2026-23074'

A use-after-free vulnerability (CVE-2026-23074) in the Linux kernel's teql queueing discipline can lead to privilege escalation on Container-Optimized OS nodes. This vulnerability affects certain versions of Red Hat Enterprise Linux 6 Extended Lifecycle Support and specific Google Kubernetes Engine (GKE) node pool versions. GKE Standard clusters are impacted, while GKE Autopilot clusters are not affected by default unless specific insecure configurations are used. GKE Sandbox clusters and bare metal GDC software are not affected. Patch versions are available for affected GKE Ubuntu node pools and Container-Optimized OS node pools. Red Hat has released kernel updates for affected Red Hat Enterprise Linux 6 Extended Lifecycle Support versions. Bare metal GDC software does not require action as it is not affected.

The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements. Security Fix(es): * kernel: page_pool: Fix use-after-free in page_pool_recycle_in_ring (CVE-2025-38129) * kernel: Linux kernel:A use-after-free in bridge multicast in br_multicast_port_ctx_init (CVE-2025-38248) * kernel: smc: Fix use-after-free in __pnet_find_base_ndev() (CVE-2025-40064) * kernel: mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats (CVE-2025-68800) * kernel: Linux kernel: Use-after-free in teql queueing discipline can lead to privilege escalation (CVE-2026-23074) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

In the Linux kernel, the following vulnerability has been resolved: net/sched: Enforce that teql can only be used as root qdisc Design intent of teql is that it is only supposed to be used as root qdisc. We need to check for that constraint. Although not important, I will describe the scenario that unearthed this issue for the curious. GangMin Kim <[email protected]> managed to concot a scenario as follows: ROOT qdisc 1:0 (QFQ) ├── class 1:1 (weight=15, lmax=16384) netem with delay 6.4s └── class 1:2 (weight=1, lmax=1514) teql GangMin sends a packet which is enqueued to 1:1 (netem). Any invocation of dequeue by QFQ from this class will not return a packet until after 6.4s. In the meantime, a second packet is sent and it lands on 1:2. teql's enqueue will return success and this will activate class 1:2. Main issue is that teql only updates the parent visible qlen (sch->q.qlen) at dequeue. Since QFQ will only call dequeue if peek succeeds (and teql's peek always returns NULL), dequeue will never be called and thus the qlen will remain as 0. With that in mind, when GangMin updates 1:2's lmax value, the qfq_change_class calls qfq_deact_rm_from_agg. Since the child qdisc's qlen was not incremented, qfq fails to deactivate the class, but still frees its pointers from the aggregate. So when the first packet is rescheduled after 6.4 seconds (netem's delay), a dangling pointer is accessed causing GangMin's causing a UAF.