Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-09-11T00:00:00 kernel: openvswitch: only skb_tx_error() a packet we are about to drop 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-367

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.

A flaw was found in openvswitch in the Linux kernel. This vulnerability occurs when the `queue_userspace_packet()` function incorrectly modifies a shared network packet buffer by stripping a critical flag. This action can lead to an unprivileged page-cache write, allowing a local attacker to modify data in memory that they should not have access to. This could potentially result in information disclosure or privilege escalation.

Red Hat Enterprise Linux 10 Affected kernel Red Hat Enterprise Linux 10 Affected kernel-rt Red Hat Enterprise Linux 6 Under investigation kernel Red Hat Enterprise Linux 7 Affected kernel Red Hat Enterprise Linux 7 Affected kernel-rt Red Hat Enterprise Linux 8 Affected kernel Red Hat Enterprise Linux 8 Affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel Red Hat Enterprise Linux 9 Affected kernel-rt Red Hat OpenShift Container Platform 4 Affected openshift/ose-rhel-coreos-8 Red Hat OpenShift Container Platform 4 Affected openshift/ose-rhel-coreos-9 https://www.cve.org/CVERecord?id=CVE-2026-89487 https://nvd.nist.gov/vuln/detail/CVE-2026-89487 https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89487.mbox