CVE-2026-74714— BPF TCP bpf_iter_tcp_established_batch 使用释放后漏洞
一分钟漏洞结论
影响对象
Linux Linux
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
在 Linux 内核中，已修复以下漏洞： bpf: tcp: 修复 bpf_iter_tcp_established_batch() 中的释放后使用（use-after-free）漏洞 会将一个处于 状态的 发布到 ehash 链表中，释放桶锁（bucket lock），然后才将 设置为 3。 无锁读者如 通过 来处理此情况，但 在持有桶锁的情况下使用普通的 ，其假设是锁保证了 。然而，这一假设对于 并不成立： 这表现为： 当发布方的 CPU 执行 覆盖计数值时，迭代器所“窃取”的引用将会丢失，导致 socket
可能的 ATT&CK 技术 1 AI
T1068 · Exploitation for Privilege Escalation影响版本矩阵 14
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | 04c7820b776f1c4b48698574c47de9e940d368e8< cc0295f89296ed351fc4b0b48fee887ba02c5d24 |
affected |
04c7820b776f1c4b48698574c47de9e940d368e8< ddbe966b5d1fe212ada749bc3d0b410f1a7dea74 |
affected | ||
04c7820b776f1c4b48698574c47de9e940d368e8< 7d2b60a4bc0499f62ff8520af6309bbe170882fd |
affected | ||
04c7820b776f1c4b48698574c47de9e940d368e8< cefcbbe20846a45f9a7dae868f7ef1000953e2df |
affected | ||
04c7820b776f1c4b48698574c47de9e940d368e8< 97e74d3e45d653c07c2d406fc530a9bbe3df8396 |
affected | ||
04c7820b776f1c4b48698574c47de9e940d368e8< e5fd3f514e27db1f05fbd72ba615d74941e23c51 |
affected | ||
5.15 |
affected | ||
< 5.15 |
unaffected | ||
| … +6 条更多 | |||
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一、 漏洞 CVE-2026-74714 基础信息
漏洞信息
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Vulnerability Title
bpf: tcp: Fix use-after-free in bpf_iter_tcp_established_batch()
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
bpf: tcp: Fix use-after-free in bpf_iter_tcp_established_batch()
reqsk_queue_hash_req() publishes a TCP_NEW_SYN_RECV request_sock onto
the ehash chain, drops the bucket lock, and only afterwards sets
rsk_refcnt to 3.
Lockless readers such as __inet_lookup_established() handle this with
refcount_inc_not_zero(), but bpf_iter_tcp_established_batch() uses plain
sock_hold() while holding the bucket lock, on the assumption that the
lock guarantees sk_refcnt > 0. That assumption does not hold for
request_sock:
CPU 0 CPU 1
----- -----
tcp_conn_request()
reqsk_queue_hash_req()
inet_ehash_insert(req)
spin_lock(bucket)
__sk_nulls_add_node_rcu(req) // rsk_refcnt == 0
spin_unlock(bucket)
bpf_iter_tcp_established_batch()
spin_lock(bucket)
sock_hold(req) <-- addition on 0
spin_unlock(bucket)
refcount_set(&req->rsk_refcnt, 3) // clobbers saturated value
which surfaces as:
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x48/0x90, CPU#1
Call Trace:
bpf_iter_tcp_established_batch+0x14e/0x170
bpf_iter_tcp_batch+0x53/0x200
bpf_iter_tcp_seq_next+0x27/0x70
bpf_seq_read+0x107/0x410
vfs_read+0xb9/0x380
The iterator's stolen reference is lost when the publishing CPU's
refcount_set() overwrites the count, leaving the socket one reference
short. When the last legitimate owner drops its reference the reqsk is
freed while still reachable, leading to use-after-free.
This reproduces in seconds with tcp_syncookies=0, a handful of threads
doing connect()/close() to a local listener while others read an
iter/tcp link in a tight loop.
Use refcount_inc_not_zero() and skip the socket on failure. A skipped
socket is still part of the bucket, so keep counting it in expected.
The reallocations are sized from expected, and a request sock whose
refcount gets published while the lock is held across the last realloc
must already have room.
A skipped socket is counted in expected but never batched, so end_sk
can be short of expected on a batch that is actually complete. Decide
completeness by whether the walk left any socket behind instead. The
WARN after the locked realloc checks the same, replacing an
end_sk == expected check that could not hold on that path since
commit cdec67a489d4 ("bpf: tcp: Make sure iter->batch always
contains a full bucket snapshot").
If every matching socket in a bucket is mid-init (refcount 0), end_sk
stays 0. Advance to the next bucket rather than returning a batch entry
that was never filled this round.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
受影响产品
二、漏洞 CVE-2026-74714 的公开POC
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CVE-2026-74714 补丁与修复 (6)
同批安全公告 · Linux · 2026-08-22 · 共 150 条
| CVE-2026-74612 | 10.0 CRITICAL | Linux内核veth模块SKB长度计算漏洞 |
| CVE-2026-74705 | 10.0 CRITICAL | UDP隧道分段潜在使用-after-free漏洞 |
| CVE-2026-74611 | 9.8 CRITICAL | TLS 1.3 乐观重试消息迭代器恢复漏洞 |
| CVE-2026-74617 | 9.8 CRITICAL | dibs: 在dibs_dev_alloc()中初始化dibs->lock |
| CVE-2026-74628 | 9.8 CRITICAL | Linux内核 x25 远程计时器释放后使用漏洞 |
| CVE-2026-74597 | 9.8 CRITICAL | Linux ip6_tunnel skb2->cb[]未清除漏洞 |
| CVE-2026-74616 | 9.8 CRITICAL | Linux内核XDP克隆数据包越界漏洞 |
| CVE-2026-74591 | 9.8 CRITICAL | Linux 内核文件映射恢复索引前重试导致漏洞 |
| CVE-2026-74688 | 9.8 CRITICAL | SCTP传输控制块移除漏洞 |
| CVE-2026-74587 | 9.8 CRITICAL | SCTP 缓存 ASCONF 块使用后释放漏洞 |
| CVE-2026-74608 | 9.8 CRITICAL | SMB客户端cifs_try_adding_channels函数中的释放后使用漏洞 |
| CVE-2026-74723 | 9.8 CRITICAL | btrfs LZO拒绝无有效头部的内联扩展 |
| CVE-2026-74730 | 9.8 CRITICAL | NFS：在FREE_STATEID调用期间锁定struct nfs_server |
| CVE-2026-74727 | 9.8 CRITICAL | OpenVPN by_id移除后跳过哈希重构 |
| CVE-2026-74586 | 9.8 CRITICAL | Linux内核SCTP对等端移除时传输未清理漏洞 |
| CVE-2026-74662 | 9.8 CRITICAL | Linux inet frags 定时器竞争条件漏洞 |
| CVE-2026-74669 | 9.8 CRITICAL | Linux IPVS IPv4选项后重定位隧道ICMP错误 |
| CVE-2026-74588 | 9.8 CRITICAL | Linux SCTP传输列表不同步漏洞 |
| CVE-2026-74712 | 9.3 CRITICAL | mlx5 vdpa 在 create_direct_keys() 中缓冲区长度修复漏洞 |
| CVE-2026-74665 | 9.1 CRITICAL | NET skb长度计算通用XDP片段调整后修复 |
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IV. Related Vulnerabilities
V. Comments for CVE-2026-74714
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