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CVE-2026-64045— ovpn: tcp - use cached peer pointer in ovpn_tcp_close()

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.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 6.16版本存在释放后重用漏洞，该漏洞源于 ovpn_tcp_close() 函数中 RCU 读取锁释放后对 peer 指针的重复引用，可能导致竞争条件，从而使攻击者触发空指针取消引用或释放后重用。

CVSS 8.4 · High EPSS 0.19% · P9

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 11851cbd60ea1e5abbd97619d69845ead99303d6< e5460eb7238c19d651a9b22b2378b587033a4095 affected
11851cbd60ea1e5abbd97619d69845ead99303d6< d3ef441907fca7c340979e577a3db3bb634bf166 affected
11851cbd60ea1e5abbd97619d69845ead99303d6< 775d8d7ad02aa345e1588424a6a8b9ae49fb9012 affected
6.16 affected
< 6.16 unaffected
6.18.34≤ 6.18.* unaffected
7.0.11≤ 7.0.* unaffected
7.1≤ * unaffected
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I. Basic Information for CVE-2026-64045

Vulnerability Information
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Vulnerability Title
ovpn: tcp - use cached peer pointer in ovpn_tcp_close()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ovpn: tcp - use cached peer pointer in ovpn_tcp_close() ovpn_tcp_close() loads the ovpn_socket via rcu_dereference_sk_user_data() under rcu_read_lock(), takes a reference on sock->peer, caches the peer pointer in a local, and drops the read lock. It then passes sock->peer (rather than the cached local) to ovpn_peer_del(), re-dereferencing the ovpn_socket after the RCU read section has ended. Unlike ovpn_tcp_sendmsg(), which uses the same "load under RCU, use after unlock" pattern but is protected by lock_sock() held across the function, ovpn_tcp_close() runs without the socket lock: inet_release() invokes sk_prot->close() without taking lock_sock first. ovpn_socket_release() can therefore complete its kref_put -> detach -> synchronize_rcu -> kfree(sock) sequence concurrently, in the window after ovpn_tcp_close() drops rcu_read_lock() but before it dereferences sock->peer. The synchronize_rcu() in ovpn_socket_release() protects readers that use the dereferenced pointer inside the RCU read section, not those that escape the pointer to a local and use it afterwards. A reproducer follows the pattern of commit 94560267d6c4 ("ovpn: tcp - don't deref NULL sk_socket member after tcp_close()"): trigger a peer removal (keepalive expiration or netlink OVPN_CMD_DEL_PEER) at the same moment userspace closes the TCP fd. That commit fixed the detach-side of the same race window; this one fixes the close-side at a different victim. Tighten the entry block to read sock->peer exactly once into the cached peer local, and route all subsequent uses (the hold check, the ovpn_peer_del() call, and the prot->close() invocation) through that local. sock->peer is only ever written once in ovpn_socket_new() under lock_sock(), before rcu_assign_sk_user_data() publishes the ovpn_socket, and is never reassigned afterwards - but the previous multi-read pattern made that invariant implicit rather than explicit. The same multi-read shape exists in ovpn_tcp_recvmsg(), ovpn_tcp_sendmsg(), ovpn_tcp_data_ready() and ovpn_tcp_write_space(); those will be cleaned up via a dedicated helper in a follow-up net-next series.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 6.16版本存在释放后重用漏洞，该漏洞源于 ovpn_tcp_close() 函数中 RCU 读取锁释放后对 peer 指针的重复引用，可能导致竞争条件，从而使攻击者触发空指针取消引用或释放后重用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 11851cbd60ea1e5abbd97619d69845ead99303d6 ~ e5460eb7238c19d651a9b22b2378b587033a4095 -
Linux Linux 6.16 -

II. Public POCs for CVE-2026-64045

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III. Intelligence Information for CVE-2026-64045

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Patches & Fixes for CVE-2026-64045 (2)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-63994 9.8 CRITICAL tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()
CVE-2026-63993 9.8 CRITICAL vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-64102 9.8 CRITICAL RDMA/siw: Reject MPA FPDU length underflow before signed receive math
CVE-2026-53399 9.8 CRITICAL nfsd: release layout stid on setlease failure
CVE-2026-53398 9.8 CRITICAL NFSD: Fix SECINFO_NO_NAME decode error cleanup
CVE-2026-64061 9.8 CRITICAL netfs: Fix early put of sink folio in netfs_read_gaps()
CVE-2026-64089 9.8 CRITICAL batman-adv: tt: fix negative last_changeset_len
CVE-2026-64091 9.8 CRITICAL batman-adv: tt: fix TOCTOU race for reported vlans
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-64125 9.8 CRITICAL net: bcmgenet: keep RBUF EEE/PM disabled
CVE-2026-64066 9.8 CRITICAL netfs: Fix netfs_read_to_pagecache() to pause on subreq failure
CVE-2026-64132 9.8 CRITICAL ipv6: ioam: refresh hdr pointer before ioam6_event()
CVE-2026-64136 9.8 CRITICAL smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
CVE-2026-63978 9.8 CRITICAL net/handshake: Drain pending requests at net namespace exit
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64045

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