CVE-2026-89787— ext4: check dir entry fits before reading the hash trailer in ext4_search_dir()
Quick assessment
Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
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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I. Basic Information for CVE-2026-89787
Vulnerability Information
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Vulnerability Title
ext4: check dir entry fits before reading the hash trailer in ext4_search_dir()
Source: 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-89787
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Other References for CVE-2026-89787 (7)
Same Patch Batch · Linux · 2026-09-16 · 276 CVEs total
| CVE-2026-89860 | scsi: qla2xxx: Initialize NVMe abort_work once at submission | |
| CVE-2026-89877 | media: saa7164: fix cleanup on resource allocation failure | |
| CVE-2026-89875 | media: ti: vpe: quiesce overflow recovery before freeing streams | |
| CVE-2026-89876 | media: tda18250: fix possible integer overflow | |
| CVE-2026-89874 | media: v4l2-async: avoid deleting unlinked ASC entry on link error | |
| CVE-2026-89872 | media: v4l2-fwnode: Fix fwnode leak in v4l2_fwnode_parse_link | |
| CVE-2026-89873 | media: v4l2-ctrls: validate HEVC EXT SPS RPS counts | |
| CVE-2026-89871 | media: video-i2c: fix kthread error pointer left in kthread_vid_cap on failure | |
| CVE-2026-89870 | media: zoran: Avoid freeing a registered video_device twice | |
| CVE-2026-89869 | media: qcom: iris: use disable_irq() during power-off | |
| CVE-2026-89868 | media: chips-media: wave5: Add timeout while stop_streaming | |
| CVE-2026-89867 | media: chips-media: wave5: Defer job_finish() only when a DEC_PIC was queued | |
| CVE-2026-89866 | media: chips-media: wave5: Resume device before setting EOS flag | |
| CVE-2026-89865 | scsi: qla2xxx: Zero SFP DMA buffer in FRU/I2C bsg handlers | |
| CVE-2026-89864 | scsi: qla2xxx: Bound i2c->length in I2C bsg handlers | |
| CVE-2026-89863 | scsi: qla2xxx: edif: Fix NULL pointer deref in RX SA delete check | |
| CVE-2026-89862 | scsi: qla2xxx: Fix BSG job leak on validate flash image error path | |
| CVE-2026-89861 | scsi: qla2xxx: Hold vport reference in qla24xx_report_id_acquisition() | |
| CVE-2026-89850 | scsi: qla2xxx: Don't query firmware state while chip is down | |
| CVE-2026-89848 | scsi: qla2xxx: Quiesce response IRQ before freeing request queue |
Showing top 20 of 276 CVEs. View all on vendor page → →
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V. Comments for CVE-2026-89787
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