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CVE-2026-74727— ovpn: skip rehash for peers already removed from by_id

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，已修复以下漏洞： ovpn：跳过对已从 by_id 表中移除的对等体的重新哈希操作 在获取 锁之前，通过调用 来解析目标对等体（peer）。在查找操作（仅增加引用计数）与后续获取 之间的时间窗口内，并发的 命令、保活超时或套接字断开连接可能会先获取 ，执行 将该对等体从所有四个哈希表中移除（按 ID、按 VPN 地址 IPv4/IPv6、按传输地址），然后释放锁。随后， 获取 并调用 ，从而将已移除的对等体重新插入到重新哈希表中。 同样的竞态条件也影响“浮动”（float）路径： 仅持有引用

AI Predicted 6.8 Difficulty: Moderate EPSS 0.21% · P11

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 1d36a36f6d5347360ef9681a05f6166683bafd1d< d20c181088984b6eaa8d7fe7cb5ab3510988df59 affected
1d36a36f6d5347360ef9681a05f6166683bafd1d< 66745480298775f188b2f5ad266643e85a90f73b affected
1d36a36f6d5347360ef9681a05f6166683bafd1d< 33ec10567fe14456063daf549fdf1a4f53448e4c affected
6.16 affected
< 6.16 unaffected
6.18.45≤ 6.18.* unaffected
7.1.9≤ 7.1.* unaffected
7.2≤ * unaffected
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I. Basic Information for CVE-2026-74727

Vulnerability Information
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Vulnerability Title
ovpn: skip rehash for peers already removed from by_id
Source: CVE Program / CVE List V5
Vulnerability Description
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().
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1d36a36f6d5347360ef9681a05f6166683bafd1d ~ d20c181088984b6eaa8d7fe7cb5ab3510988df59 -
Linux Linux 6.16 -

II. Public POCs for CVE-2026-74727

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III. Intelligence Information for CVE-2026-74727

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Patches & Fixes for CVE-2026-74727 (3)

Same Patch Batch · Linux · 2026-08-22 · 150 CVEs total

CVE-2026-74638 drm/v3d: Serialize the scheduler timeout handlers
CVE-2026-74621 net/sched: act_ct: fix sk_buff leak when the header checks reject a packet
CVE-2026-74622 net: atlantic: free RX pages of consumed but not refilled buffers
CVE-2026-74623 net: atlantic: free stranded TX buffers on ring deinit
CVE-2026-74624 netfilter: nf_conntrack: defer invalid log until after unlock
CVE-2026-74625 netfilter: bridge: release template ct on non-IP path
CVE-2026-74627 net: devmem: prevent net-iov / page mixing
CVE-2026-74626 NTB: ntb_netdev: Preserve RX queue depth on allocation failure
CVE-2026-74628 net/x25: fix use-after-free of the socket by its timers
CVE-2026-74629 net/dibs: Correct freeing of dmb_clientid_arr
CVE-2026-74631 net: smc: fix splice entry lifetime imbalance in smc_rx_splice
CVE-2026-74630 ipv6: prevent in6_dev_get() from resurrecting inet6_dev
CVE-2026-74632 mm/huge_memory: fix huge_zero_pfn race
CVE-2026-74633 tracing: Fix NULL pointer dereference in module event cache removal
CVE-2026-74634 ring-buffer: Prevent subbuf order change when resizing is disabled
CVE-2026-74635 fbdev: bitblit: bound-check glyph index in bit_cursor()
CVE-2026-74636 tracing: Fix race between update_event_fields and, event_define_fields
CVE-2026-74637 perf/core: Fix group leader use-after-free after sibling detach
CVE-2026-74639 ALSA: us144mkii: re-anchor capture URBs on resubmission
CVE-2026-74650 staging: rtl8723bs: fix OOB read in WMM_param_handler()

Showing top 20 of 150 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74727

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