CVE-2026-92499— ext4 readdir偏移验证前访问目录项漏洞
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： ext4：在访问目录项之前验证 readdir 偏移量 当 从一个无效位置恢复时，损坏的目录会触发以下 KASAN 报告： 由于越界访问落在相邻的已释放页中，KASAN 将其报告为“释放后使用（use-after-free）”。目录缓冲区本身仍被引用。 会使目录 cookie 失效，使得 从块起始位置重新扫描目录项。该重新扫描过程在向前推进前仅检查 的下界。因此，损坏的 可能将偏移量定位到块中空间不足以容纳完整目录项的位置。重新扫描本身可能会解引用该被截断的项，或者主循环可
影响版本矩阵 8
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | ac27a0ec112a089f1a5102bc8dffc79c8c815571< 64d445d40e5ea4c4d4d88880db753b370cb69161 |
affected |
ac27a0ec112a089f1a5102bc8dffc79c8c815571< b4c728577933753180e3e97f08424d5bcaff705e |
affected | ||
ac27a0ec112a089f1a5102bc8dffc79c8c815571< bc4b7b0414c33b2c8898eb04386df0d21a13dad8 |
affected | ||
2.6.19 |
affected | ||
< 2.6.19 |
unaffected | ||
6.18.52≤ 6.18.* |
unaffected | ||
7.2.6≤ 7.2.* |
unaffected | ||
7.3-rc1≤ * |
unaffected |
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一、 漏洞 CVE-2026-92499 基础信息
漏洞信息
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Vulnerability Title
ext4: validate readdir offset before accessing dirent
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
ext4: validate readdir offset before accessing dirent
A corrupted directory can trigger the following KASAN report when
ext4_readdir() resumes from an invalid position:
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x5ef/0x820
Read of size 2 at addr ffff88810a646000 by task repro_linear/509
Call Trace:
<TASK>
dump_stack_lvl+0x53/0x70
print_report+0xd0/0x630
kasan_report+0xce/0x100
__ext4_check_dir_entry+0x5ef/0x820
ext4_readdir+0xcde/0x2b70
iterate_dir+0x1a1/0x520
__x64_sys_getdents64+0x12b/0x220
do_syscall_64+0xf9/0x540
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
KASAN reports use-after-free because the out-of-bounds access lands in an
adjacent freed page. The directory buffer itself is still referenced.
ext4_dir_llseek() invalidates the directory cookie so that ext4_readdir()
rescans directory entries from the start of the block. The rescan checks
only the lower bound of rec_len before advancing. A corrupted rec_len can
therefore place the offset where the block has insufficient space for a
complete directory entry. The rescan itself may dereference that truncated
entry, or the main loop may pass it to __ext4_check_dir_entry(). The latter
reads de->rec_len before validating the range. For example:
block offset 0 4092 4096
|---- de1.rec_len = 4092 -----|----|
de2.inode
| de2.rec_len
^ OOB, reported as UAF
de2 starts at offset 4092 in this 4 KiB block. Its four-byte inode fits in
the block, but its rec_len starts at offset 4096 and crosses the boundary.
The minimum safe length is inode-dependent. Encrypted and casefolded
directory entries need eight additional hash bytes, while a valid metadata
checksum tail is only 12 bytes.
Cache the metadata checksum feature state and derive the minimum directory
entry length from the on-disk format. Use it to bound both the rescan and
the offset passed to the main loop. Report an offset in a truncated block
tail and skip the remainder of the block, while continuing to accept an
offset exactly at the block boundary.
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
受影响产品
二、漏洞 CVE-2026-92499 的公开POC
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|---|
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CVE-2026-92499 补丁与修复 (3)
同批安全公告 · Linux · 2026-09-17 · 共 600 条
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| CVE-2026-90151 | 9.8 CRITICAL | NFSv4客户端分配失败回调处理漏洞 |
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| CVE-2026-90367 | 8.8 HIGH | Linux内核MT7996驱动死锁漏洞 |
| CVE-2026-90329 | 8.8 HIGH | Linux 内核 HID 驱动探测清理同步漏洞 |
| CVE-2026-93189 | 8.8 HIGH | Linux HID核心使用已释放内存漏洞 |
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| CVE-2026-90286 | 8.8 HIGH | AMDGPU GFX6 计算队列PFP使用漏洞 |
| CVE-2026-93042 | 8.8 HIGH | Linux内核dmaengine模块资源耗尽漏洞 |
| CVE-2026-90256 | 8.8 HIGH | Linux Bluetooth L2CAP 远程代码执行漏洞 |
| CVE-2026-90380 | 8.8 HIGH | MT76驱动 mt792x 使用释放后内存漏洞 |
| CVE-2026-90381 | 8.8 HIGH | Linux内核mt76驱动无线信道切换漏洞 |
| CVE-2026-90425 | 8.8 HIGH | Linux内核 5.x 内核漏洞 |
显示前 20 条，共 600 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-92499
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