CVE-2026-89762— 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基金会开源的一个操作系统内核。 Linux kernel 2.6.36版本存在安全漏洞，该漏洞源于AppArmor的begin_current_label_crit_section()函数在检查到当前凭据关联的标签已过期时直接替换凭据，未正确处理凭据引用计数，可能导致凭据释放后重用（UAF），进而造成内核崩溃。
可能的 ATT&CK 技术 1 AI
T1059 · Command and Scripting Interpreter影响版本矩阵 10
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | c75afcd153f6147d3b094f45a1d87e5df7f4f053< 361488984d668235438faac28635f3632351407f |
affected |
c75afcd153f6147d3b094f45a1d87e5df7f4f053< 587a6a92b93ec314c583bbf747413af170d42540 |
affected | ||
c75afcd153f6147d3b094f45a1d87e5df7f4f053< 580f777d6d9fd07fc034bd1aeba5c30fd48871a2 |
affected | ||
c75afcd153f6147d3b094f45a1d87e5df7f4f053< 3f4ae5fab613dca01d6a2a8210dd832e009fcf47 |
affected | ||
2.6.36 |
affected | ||
< 2.6.36 |
unaffected | ||
6.12.109≤ 6.12.* |
unaffected | ||
6.18.50≤ 6.18.* |
unaffected | ||
| … +2 条更多 | |||
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一、 漏洞 CVE-2026-89762 基础信息
漏洞信息
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Vulnerability Title
apparmor: fix cred UAF caused by begin_current_label_crit_section()
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix cred UAF caused by begin_current_label_crit_section()
AppArmor's begin_current_label_crit_section() is a scary function called
from lots of LSM hooks (in particular VFS/socket-related ones) that checks
if the label referenced by the current creds is marked FLAG_STALE, and if
so, attempts to use aa_replace_current_label() to replace the creds with an
updated version that uses a new label.
The first problem with this is that it would directly lead to UAF of
`struct cred` if anything in the kernel takes a pointer to the current
creds and accesses these past a security hook invocation that replaces
creds, like so:
```
const struct cred *cred = current_cred();
alloc_file_pseudo(...);
uid_t uid = cred->euid;
```
I don't know if anything in the kernel actually does this, but I think it
is very surprising that this pattern could lead to UAF.
The second problem is that things go wrong when aa_replace_current_label()
runs with overridden credentials. aa_replace_current_label() bails out if
`current_cred() != current_real_cred()` (mirroring the check in
proc_pid_attr_write()), but this check can't actually reliably detect
overridden credentials because the overridden creds can be the same as the
objective creds.
So in approximately the following scenario, things go wrong:
1. task begins with <creds A> (as both objective and subjective creds),
with refcount=2
2. task grabs an extra reference on <creds A> for overriding
3. task calls override_creds(<creds A>), which returns a pointer to the old
subjective creds (<creds A>)
4. task enters AppArmor LSM hook
5. AppArmor checks that objective/subjective creds are equal
6. AppArmor replaces both cred pointers with <creds B> and drops 2 refs on
<creds A>
7. task leaves AppArmor LSM hook
8. task calls revert_creds(<creds A>)
9. now task->cred is <creds A> while task->real_cred is <creds B>, but the
task_struct logically holds two references to <creds B>
10. another task drops the extra reference on <creds A> that was used for
overriding, refcount drops to 0
11. now task->real_cred points to freed creds
At this point, any access to current_cred() will be UAF.
I have a test case where I run aa-disable on a profile while a process
using that profile is blocked on splice() from a FUSE passthrough file into
a full pipe; after the profile update, the pipe becomes empty, splice()
resumes, the credentials go out of sync, and a subsequent getuid() syscall
results in a KASAN UAF splat.
To fix this, instead of directly replacing creds, do it via task_work that
will run at the end of the current syscall. (The point in time at which the
cred replacement happens should have no correctness impact; it is just a
performance optimization to avoid unnecessarily touching the refcount of
the new label.)
Note that AppArmor still performs direct cred replacements in the
sb_pivotroot LSM hook after this change, and that direct cred replacements
can still happen in VFS ->write() callbacks via proc_pid_attr_write().
There are two options for what to do with aa_dup_task_ctx(): Either
explicitly reset new->label_replacement_pending after the entire
aa_task_ctx has been copied, or switch to manually copying members over.
I am switching to manually copying members over because that should make
bugs more obvious.
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
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基金会开源的一个操作系统内核。 Linux kernel 2.6.36版本存在安全漏洞，该漏洞源于AppArmor的begin_current_label_crit_section()函数在检查到当前凭据关联的标签已过期时直接替换凭据，未正确处理凭据引用计数，可能导致凭据释放后重用（UAF），进而造成内核崩溃。
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-2026-89762 的公开POC
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|---|
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CVE-2026-89762 补丁与修复 (4)
同批安全公告 · Linux · 2026-09-11 · 共 431 条
| CVE-2026-89669 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89536 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89533 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-81002 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89643 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89526 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89652 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89651 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89653 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89654 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89656 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89655 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89712 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89658 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89660 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89659 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89708 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89662 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89689 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-89686 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
显示前 20 条，共 431 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-89762
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