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CVE-2026-92499— ext4: validate readdir offset before accessing dirent

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.

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

AI Predicted 4.5 Difficulty: Moderate EPSS 0.21% · P10

Affected Version Matrix 8

VendorProduct Version RangeStatus
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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I. Basic Information for CVE-2026-92499

Vulnerability Information
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Vulnerability Title
ext4: validate readdir offset before accessing dirent
Source: 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.
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

Vendor Product Affected Versions CPE Subscribe
Linux Linux ac27a0ec112a089f1a5102bc8dffc79c8c815571 ~ 64d445d40e5ea4c4d4d88880db753b370cb69161 -
Linux Linux 2.6.19 -

II. Public POCs for CVE-2026-92499

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III. Intelligence Information for CVE-2026-92499

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Patches & Fixes for CVE-2026-92499 (3)

Same Patch Batch · Linux · 2026-09-17 · 600 CVEs total

CVE-2026-92489 9.8 CRITICAL xfrm: Fix skb double-free in xfrm_dev_direct_output()
CVE-2026-90235 9.8 CRITICAL sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
CVE-2026-90173 9.8 CRITICAL smb: smbdirect: free completion queues with ib_free_cq()
CVE-2026-90104 9.8 CRITICAL NFSv4.1: zero referring call lists before decoding
CVE-2026-90151 9.8 CRITICAL NFSv4: remove callback IDR entry on client allocation failure
CVE-2026-90110 9.4 CRITICAL inetpeer: randomize RB-tree node comparison using SipHash
CVE-2026-90230 9.1 CRITICAL nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate()
CVE-2026-90414 9.1 CRITICAL IB/isert: reject PDUs declaring more data than was received
CVE-2026-90413 9.1 CRITICAL IB/isert: reject login PDUs declaring more data than was received
CVE-2026-90367 8.8 HIGH wifi: mt76: mt7996: hold dev->mt76.mutex while disabling tx worker in SER
CVE-2026-90329 8.8 HIGH HID: synchronize input before cleaning up a failed probe
CVE-2026-93189 8.8 HIGH HID: core: quiesce input in hid_hw_stop() to prevent use-after-free
CVE-2026-90240 8.8 HIGH iommu/vt-d: Flush context cache with correct SID when tearing down aliases
CVE-2026-90357 8.8 HIGH wifi: mt76: mt7915: unlink TWT flow if the MCU rejects the agreement
CVE-2026-90286 8.8 HIGH drm/amdgpu/gfx6: Use PFP on the compute queues too
CVE-2026-93042 8.8 HIGH dmaengine: dw-edma: Terminate all descriptors without callbacks
CVE-2026-90256 8.8 HIGH Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind
CVE-2026-90380 8.8 HIGH wifi: mt76: mt792x: fix use-after-free in mt76_rx_poll_complete
CVE-2026-90381 8.8 HIGH wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx()
CVE-2026-90425 8.8 HIGH iommu/tegra241-cmdqv: Require exactly one Stream ID for a vSID

Showing top 20 of 600 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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