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CVE-2026-89487

openvswitch: only skb_tx_error() a packet we are about to drop

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.11, 3.13, 5.10.270, 5.15.221, 6.1.188, and 4 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in 5de5d554141a15b3f1f5c978fd9f7f4fd6d0600a; From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in 48db11e115d1b232edc5591604adc6eda95cd545; From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in 4477222e2916a18e273edc139c955ade6bbb7a69; From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in 4d5c460ef8754be1d43b16dbf02695b008b207d6; From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in 6767d70cf46f65807a6a4c4406a518e6c12e36ae; From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in e41a59fc056f63a7a1f42788913c53cc48d744aa; From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in 5d85eef222cfd28e73deed7402c100229e8b9e6e; From 36d5fe6a000790f56039afe26834265db0a3ad4c · fixed in 0dbc2398fca3bb33eda963849f865ddb1b3aa05e; From 3.10.51 · fixed in 3.11; From 3.12.40 · fixed in 3.13

  • Linux Linux

    3.14

  • KernelLinux

    From 3.14.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 8

git.kernel.org