CVE-2026-89787— Ext4 文件系统 ext4_search_dir 缓冲区溢出漏洞
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。
In the Linux kernel, the following vulnerability has been resolved: ext4: check dir entry fits before reading the hash trailer in ext4_search_dir() For casefolded encrypted directories ext4 stores an 8-byte hash trailer after the name (EXT4_DIRENT_HASHES()), a
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一、 漏洞 CVE-2026-89787 基础信息
漏洞信息
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Vulnerability Title
ext4: check dir entry fits before reading the hash trailer in ext4_search_dir()
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
ext4: check dir entry fits before reading the hash trailer in ext4_search_dir()
For casefolded encrypted directories ext4 stores an 8-byte hash trailer
after the name (EXT4_DIRENT_HASHES()), at an offset derived from
de->name_len. On the sb_no_casefold_compat_fallback() path ext4_match()
reads that trailer, but ext4_search_dir()'s by-hand pre-check only tests
de->name + de->name_len <= dlimit, which proves the name fits, not the
rounded trailer. A crafted entry whose name ends at the block boundary
passes the check while EXT4_DIRENT_HASHES(de) lands past the block end,
so ext4_match() reads out of bounds on an ordinary lookup. KASAN reports
it as a use-after-free when the page after the directory block holds a
freed object:
BUG: KASAN: use-after-free in ext4_match (fs/ext4/namei.c:1435)
Read of size 4 at addr ffff888010458000 by task exploit
Call Trace:
ext4_match (fs/ext4/namei.c:1435)
ext4_search_dir (fs/ext4/namei.c:1470)
__ext4_find_entry (fs/ext4/namei.c:1268 fs/ext4/namei.c:1632)
ext4_lookup (fs/ext4/namei.c:1703 fs/ext4/namei.c:1769)
...
filename_lookup (fs/namei.c:2842)
vfs_statx (fs/stat.c:353)
__do_sys_newfstatat (fs/stat.c:538)
do_syscall_64 (arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
Require, for hash-in-dirent directories, that the whole entry including
the rounded trailer fits before calling ext4_match(). This is the same
bound ext4_check_dir_entry() already enforces via ext4_dir_rec_len(), so
no well-formed entry is rejected. The other caller, ext4_find_dest_de(),
runs ext4_check_dir_entry() first and is unaffected.
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-2026-89787 的公开POC
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CVE-2026-89787 其他参考 (7)
同批安全公告 · Linux · 2026-09-16 · 共 20 条
| CVE-2026-89784 | SunRPC rpcb_register_inet4/6 返回值检查漏洞 | |
| CVE-2026-89774 | Linux内核蓝牙SCO连接准备函数缺陷 | |
| CVE-2026-89775 | KVM arm64 VNCR TLB大小计算漏洞 | |
| CVE-2026-89776 | vxlan: vnifilter 属性长度校验缺陷 | |
| CVE-2026-89778 | isofs 空 zisofs 块页面数组越界访问漏洞 | |
| CVE-2026-89777 | vfio/pci初始化失败时未清空msi_perm内存泄漏 | |
| CVE-2026-89779 | NTFS3文件系统efs size验证缺陷 | |
| CVE-2026-89781 | Linux NTFS3 驱动越界读取漏洞 | |
| CVE-2026-89780 | Qualcomm rmnet 去聚合帧 skb->dev 恢复漏洞 | |
| CVE-2026-89782 | NTFS3 fs/ntfs3 拒绝重启表增长漏洞 | |
| CVE-2026-89793 | ublk 只读设备 mmap 权限清除漏洞 | |
| CVE-2026-89783 | Linux内核 xfrm6 越界写入漏洞 | |
| CVE-2026-89785 | Linux内核ntfs3驱动越界读取漏洞 | |
| CVE-2026-89786 | Linux内核ext4文件系统越界读取漏洞 | |
| CVE-2026-89788 | Linux kernel ksmbd 释放后使用漏洞 | |
| CVE-2026-89790 | Linux内核ipv6模块除零漏洞 | |
| CVE-2026-89789 | Linux内核GTP驱动UAF漏洞 | |
| CVE-2026-89791 | Linux perf 工具竞态导致 UAF 漏洞 | |
| CVE-2026-89792 | Linux ksmbd 共享配置越界读取漏洞 |
IV. Related Vulnerabilities
V. Comments for CVE-2026-89787
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