CVE-2026-31711— Linux kernel 安全漏洞
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。
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于smb服务器在传输分配失败时未正确减少active_num_conn计数，导致连接泄漏。
影响版本矩阵 18
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | 4210c3555db4b38bade92331b153e583261f05f9< dc2e7d595d68cf1be1ba64e3d30ebf3266bf7242 |
affected |
d5d7847e57ac69fa99c18b363a34419bcdb5a281< 60734c8bc3b4aa0672e251f08dda81977e4b5387 |
affected | ||
0d0d4680db22eda1eea785c47bbf66a9b33a8b16< 97f8d2648ef4871e4cd335e2d769cb40054a6772 |
affected | ||
0d0d4680db22eda1eea785c47bbf66a9b33a8b16< 295a9fc6789d1011c36ded9f0f2907bb34fa0de4 |
affected | ||
0d0d4680db22eda1eea785c47bbf66a9b33a8b16< 283027aa93380380a0994f35dde3ec95318f2654 |
affected | ||
0d0d4680db22eda1eea785c47bbf66a9b33a8b16< fb48185bcd946d42de7017cf27f912f8ab26acf0 |
affected | ||
0d0d4680db22eda1eea785c47bbf66a9b33a8b16< 6551300dc452ac16a855a83dbd1e74899542d3b3 |
affected | ||
5.15.91< 5.15.210 |
affected | ||
| … +10 条更多 | |||
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一、 漏洞 CVE-2026-31711 基础信息
漏洞信息
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Vulnerability Title
smb: server: fix active_num_conn leak on transport allocation failure
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
smb: server: fix active_num_conn leak on transport allocation failure
Commit 77ffbcac4e56 ("smb: server: fix leak of active_num_conn in
ksmbd_tcp_new_connection()") addressed the kthread_run() failure
path. The earlier alloc_transport() == NULL path in the same
function has the same leak, is reachable pre-authentication via any
TCP connect to port 445, and was empirically reproduced on UML
(ARCH=um, v7.0-rc7): a small number of forced allocation failures
were sufficient to put ksmbd into a state where every subsequent
connection attempt was rejected for the remainder of the boot.
ksmbd_kthread_fn() increments active_num_conn before calling
ksmbd_tcp_new_connection() and discards the return value, so when
alloc_transport() returns NULL the socket is released and -ENOMEM
returned without decrementing the counter. Each such failure
permanently consumes one slot from the max_connections pool; once
cumulative failures reach the cap, atomic_inc_return() hits the
threshold on every subsequent accept and every new connection is
rejected. The counter is only reset by module reload.
An unauthenticated remote attacker can drive the server toward the
memory pressure that makes alloc_transport() fail by holding open
connections with large RFC1002 lengths up to MAX_STREAM_PROT_LEN
(0x00FFFFFF); natural transient allocation failures on a loaded
host produce the same drift more slowly.
Mirror the existing rollback pattern in ksmbd_kthread_fn(): on the
alloc_transport() failure path, decrement active_num_conn gated on
server_conf.max_connections.
Repro details: with the patch reverted, forced alloc_transport()
NULL returns leaked counter slots and subsequent connection
attempts -- including legitimate connects issued after the
forced-fail window had closed -- were all rejected with "Limit the
maximum number of connections". With this patch applied, the same
connect sequence produces no rejections and the counter cycles
cleanly between zero and one on every accept.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于smb服务器在传输分配失败时未正确减少active_num_conn计数，导致连接泄漏。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD
受影响产品
二、漏洞 CVE-2026-31711 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-31711 补丁与修复 (7)
同批安全公告 · Linux · 2026-05-01 · 共 146 条
| CVE-2026-43011 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43037 | 9.8 CRITICAL | Linux kernel 缓冲区错误漏洞 |
| CVE-2026-31705 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43038 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43039 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-31718 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43018 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31773 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31739 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31735 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31717 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43048 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31709 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31706 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31712 | 8.3 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31771 | 8.1 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31779 | 8.1 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43051 | 8.1 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31708 | 8.1 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-31695 | 7.8 HIGH | Linux kernel 安全漏洞 |
显示前 20 条，共 146 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-31711
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