CVE-2026-89487
UnknownSummary
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).
Risk Assessment
Allows an unprivileged user to write to page-cache memory, potentially leading to data corruption or privilege escalation. Requires MSG_ZEROCOPY and an openvswitch setup with ESP-in-UDP.
Recommendation
Update the Linux kernel to a version with the fix that moves skb_tx_error() to the flow-miss drop path. Until patched, consider disabling MSG_ZEROCOPY or limiting openvswitch use with ESP-in-UDP.
Other vulnerabilities in Linux kernel (openvswitch)
See all- CVE-2026-89488Unknown
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.
- 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: only skb_tx_error() a packet we are about to drop queue_userspace_packet() borrows the packet skb -- it only copies it into a private netlink message (user_skb) and does not own it; on return do_execute_actions() keeps forwarding it through the flow's remaining actions. Its error path nevertheless calls skb_tx_error(skb), which via skb_zcopy_clear() does skb_shinfo(skb)->flags &= ~SKBFL_ALL_ZEROCOPY, stripping SKBFL_SHARED_FRAG from that live skb (skb_tx_error()'s kerneldoc says "skb must be freed afterwards"). For a MSG_ZEROCOPY skb carrying page-cache frags, SKBFL_SHARED_FRAG is what makes esp_input() skb_cow_data() before in-place AEAD; once it is stripped a later local ESP-in-UDP delivery decrypts in place over pages the sender does not own -- an unprivileged page-cache write (the "Fragnesia" primitive). do_execute_actions() ignores output_userspace()'s return value, so any action after a failed USERSPACE upcall inherits the stripped skb. Move the skb_tx_error() to the flow-miss drop path - the "default" branch of ovs_dp_process_packet()'s switch(error), before kfree_skb(). The call has been here since commit 36d5fe6a0007 ("core, nfqueue, openvswitch: Orphan frags in skb_zerocopy and handle errors") but was harmless until esp_input() began relying on SKBFL_SHARED_FRAG to gate in-place decrypt; only then did stripping it on a still-forwarded skb become a page-cache write primitive.