CVE-2026-43420— 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ceph异步unlink操作在收到完成前提前减少i_nlink计数器，导致与其他客户端删除操作竞争时发生i_nlink下溢。
可能的 ATT&CK 技术 1 AI
T1499 · Endpoint Denial of Service影响版本矩阵 18
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | 2ccb45462aeaf0831397b90d31d3d50a7704fa1f< 9b31e88ac5623d15c8bc46f69dfe1d3b43a8f67c |
affected |
2ccb45462aeaf0831397b90d31d3d50a7704fa1f< 6d5fd8bb574bef039eb3b738e523870433a2aeb9 |
affected | ||
2ccb45462aeaf0831397b90d31d3d50a7704fa1f< fcc477a6e8856c8a42b3c9e171724d8d6dfadd06 |
affected | ||
2ccb45462aeaf0831397b90d31d3d50a7704fa1f< b3f5513141ecc6b277a8f7b7efe58a0cf9a5e859 |
affected | ||
2ccb45462aeaf0831397b90d31d3d50a7704fa1f< aedd29386b23f3e1e6818943e11abfff2953732f |
affected | ||
2ccb45462aeaf0831397b90d31d3d50a7704fa1f< 7db008e85a5d17b64bc5390b828bf457ae91a415 |
affected | ||
2ccb45462aeaf0831397b90d31d3d50a7704fa1f< 8975b85b0d45ca811ace6fac5907652f2310e5ac |
affected | ||
2ccb45462aeaf0831397b90d31d3d50a7704fa1f< ce0123cbb4a40a2f1bbb815f292b26e96088639f |
affected | ||
| … +10 条更多 | |||
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一、 漏洞 CVE-2026-43420 基础信息
漏洞信息
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Vulnerability Title
ceph: fix i_nlink underrun during async unlink
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
ceph: fix i_nlink underrun during async unlink
During async unlink, we drop the `i_nlink` counter before we receive
the completion (that will eventually update the `i_nlink`) because "we
assume that the unlink will succeed". That is not a bad idea, but it
races against deletions by other clients (or against the completion of
our own unlink) and can lead to an underrun which emits a WARNING like
this one:
WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68
Modules linked in:
CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655
Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023
pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : drop_nlink+0x50/0x68
lr : ceph_unlink+0x6c4/0x720
sp : ffff80012173bc90
x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680
x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647
x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203
x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365
x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec
x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74
x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94
x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002
x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8
Call trace:
drop_nlink+0x50/0x68 (P)
vfs_unlink+0xb0/0x2e8
do_unlinkat+0x204/0x288
__arm64_sys_unlinkat+0x3c/0x80
invoke_syscall.constprop.0+0x54/0xe8
do_el0_svc+0xa4/0xc8
el0_svc+0x18/0x58
el0t_64_sync_handler+0x104/0x130
el0t_64_sync+0x154/0x158
In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the
CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion.
Meanwhile, between this call and the following drop_nlink() call, a
worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or
just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own
completion). These will lead to a set_nlink() call, updating the
`i_nlink` counter to the value received from the MDS. If that new
`i_nlink` value happens to be zero, it is illegal to decrement it
further. But that is exactly what ceph_unlink() will do then.
The WARNING can be reproduced this way:
1. Force async unlink; only the async code path is affected. Having
no real clue about Ceph internals, I was unable to find out why the
MDS wouldn't give me the "Fxr" capabilities, so I patched
get_caps_for_async_unlink() to always succeed.
(Note that the WARNING dump above was found on an unpatched kernel,
without this kludge - this is not a theoretical bug.)
2. Add a sleep call after ceph_mdsc_submit_request() so the unlink
completion gets handled by a worker thread before drop_nlink() is
called. This guarantees that the `i_nlink` is already zero before
drop_nlink() runs.
The solution is to skip the counter decrement when it is already zero,
but doing so without a lock is still racy (TOCTOU). Since
ceph_fill_inode() and handle_cap_grant() both hold the
`ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this
seems like the proper lock to protect the `i_nlink` updates.
I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using
`afs_vnode.cb_lock`). All three have the zero check as well.
来源: CVE Program / CVE List V5
CVSS Information
N/A
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ceph异步unlink操作在收到完成前提前减少i_nlink计数器，导致与其他客户端删除操作竞争时发生i_nlink下溢。
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-2026-43420 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-43420 补丁与修复 (8)
同批安全公告 · Linux · 2026-05-08 · 共 197 条
| CVE-2026-43384 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43341 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43304 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43379 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43378 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43465 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43414 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43376 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43402 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43383 | 9.4 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43407 | 9.1 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43406 | 9.1 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-43284 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43334 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43322 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43403 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43391 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43291 | 8.3 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43466 | 8.2 HIGH | Linux kernel 安全漏洞 |
| CVE-2026-43365 | 8.2 HIGH | Linux kernel 安全漏洞 |
显示前 20 条，共 197 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-43420
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