CVE-2026-89488
UnknownSummary
In the Linux kernel, the openvswitch module has a use-after-free in CT limit teardown. The CT limit pointer was not removed from readers nor protected by an RCU grace period, so packet processing could dereference freed state when the network namespace is torn down. An unprivileged user can trigger this from a user and network namespace.
Risk Assessment
Can cause a slab-use-after-free in the kernel, potentially leading to privilege escalation or system instability triggered by an unprivileged user. Environments using containers and network namespaces are at real risk.
Recommendation
Update the Linux kernel to a version containing the openvswitch fix (RCU publication of the CT limit pointer). If patching is not possible, restrict unprivileged users from creating network namespaces.
Other vulnerabilities in Linux kernel (openvswitch)
See all- CVE-2026-89487Unknown
In the Linux kernel, openvswitch's queue_userspace_packet() calls skb_tx_error() on a packet it does not own and that is still being forwarded. This strips SKBFL_SHARED_FRAG from the live skb, causing a later local ESP-in-UDP delivery to decrypt in place over pages the sender does not own, enabling an unprivileged page-cache write (the "Fragnesia" primitive).
- CVE-2026-80994Unknown
In the Linux kernel, the openvswitch module has a use-after-free vulnerability involving the flow->mask pointer during flow deletion (CMD_DEL). The mask pointer is freed via RCU, but ovs_flow_cmd_fill_info() uses it after the flow is removed from the table without first taking the RCU read lock. This creates a race condition and can cause a kernel crash (KASAN slab-use-after-free) in the window between removal and info filling.
- CVE-2026-46165Medium
A vulnerability has been identified in the Linux kernel that leads to self-deadlock when removing tunnel ports in openvswitch. The issue arises from improper management of RCU and RTNL contexts during device removal.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: openvswitch: Fix CT limit teardown use-after-free Packet processing uses CT limit state under RCU, while netns teardown frees that state under ovs_mutex. The CT limit pointer was neither removed from readers nor protected by a grace period, allowing packet processing to dereference the freed state. An unprivileged user can trigger this bug from a user and network namespace, causing a slab-use-after-free in ovs_ct_execute() when the netns is torn down. Publish the CT limit pointer through RCU, remove it before teardown, and wait for readers before freeing its contents. Keep ovs_mutex around individual CT limit updates, and use the RCU read-side lock while GET traverses the RCU-protected limit lists. Netns teardown detaches the RCU-protected CT limit state in the pernet .pre_exit callback while holding ovs_mutex. The pernet core guarantees an RCU grace period between the .pre_exit and .exit callbacks, so the .exit callback completes the teardown without adding any extra synchronization. The netlink command handlers do not need NULL checks because the userspace netlink socket holds an active reference to its network namespace while a request is processed. The per-netns exit path therefore cannot run concurrently with SET, DEL, or GET for that socket's namespace.