---
id: CVE-2026-74727
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ovpn: skip rehash for peers already removed from by_id

  ovpn_nl_peer_set_doit() resolves the target peer via
  ovpn_peer_get_by_id() before taking ovpn->lock
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ovpn: skip rehash for peers already removed from by_id

  ovpn_nl_peer_set_doit() resolves the target peer via
  ovpn_peer_get_by_id() before taking ovpn->lock. In the wind…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
published: '2026-08-22'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:10:00.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74727'
references:
  - url: 'https://git.kernel.org/stable/c/33ec10567fe14456063daf549fdf1a4f53448e4c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/66745480298775f188b2f5ad266643e85a90f73b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d20c181088984b6eaa8d7fe7cb5ab3510988df59'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - exploit-available
epss: 0.00649
epssPercentile: 0.49768
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/Kosifuchs/ovpn-kernel-backport'
  checkedAt: '2026-10-14T13:31:34.736Z'
exploitAvailable: true
ingestedAt: '2026-10-14T13:30:58.549Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

ovpn: skip rehash for peers already removed from by_id

ovpn_nl_peer_set_doit() resolves the target peer via
ovpn_peer_get_by_id() before taking ovpn->lock. In the window between
the lookup (which only takes a refcount) and the subsequent
spin_lock_bh(&ovpn->lock), a concurrent OVPN_CMD_PEER_DEL, keepalive
expiry, or socket teardown can take ovpn->lock first, run
ovpn_peer_remove() to unhash the peer from all four tables (by_id,
by_vpn_addr4/6, by_transp_addr) and release the lock. set_doit then
acquires ovpn->lock and calls ovpn_peer_hash_vpn_ip(), which
re-inserts the now-removed peer back into the rehashing tables.

The same race affects the float path: ovpn_peer_endpoints_update()
holds only a refcount and acquires ovpn->lock very late (after async
AEAD decrypt and a netlink notification), then rehashes the peer
in the by_transp_addr table.

The resurrected peer becomes reachable again from the RX lookup
(ovpn_peer_get_by_transp_addr) and the TX VPN-IP lookup, even though
userspace believes it is gone. Once the data-path refcount drops the
peer is freed via call_rcu while the hash entries embedded in it
remain linked, opening a UAF window.

Bail out of the rehash when hash_entry_id is unhashed, mirroring
the sentinel already used by ovpn_peer_remove() to detect the
already-removed state. The check is safe under ovpn->lock, which
serializes every mutation of hash_entry_id, and is a no-op for the
add path because ovpn_peer_add_mp() inserts hash_entry_id before
calling ovpn_peer_hash_vpn_ip().

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.