What’s Vulnerable › Vulnerabilities

CVE-2023-53826: ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-09 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show() Wear-leveling entry could be freed in error path, which may be accessed again in eraseblk_count_seq_show(), for example: __erase_worker eraseblk_count_seq_show wl = ubi->lookuptbl[*block_number] if (wl) wl_entry_destroy ubi->lookuptbl[e->pnum] = NULL kmem_cache_free(ubi_wl_entry_slab, e) erase_count = wl->ec // UAF! Wear-leveling entry updating/accessing in ubi->lookuptbl should be protected by ubi->wl_lock, fix it by adding ubi->wl_lock to serialize wl entry accessing between wl_entry_destroy() and eraseblk_count_seq_show(). Fetch a reproducer in [Link].

Affected products

• Linux kernel: 2.6.22 — fixed in 6.3

How to fix

Upgrade to a fixed version: Linux kernel 6.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/1cb14c06d6035539ef4215c4ba0871aea71d7c38
• https://git.kernel.org/stable/c/3f9b63dfce44a7c3c095dd93d910408e07ab1845
• https://git.kernel.org/stable/c/79548ccdd992707879b4b683b7251c58ddf26f12
• https://git.kernel.org/stable/c/84250da1c63cb7d421a3b4812b5c2ce2e47d31a1
• https://git.kernel.org/stable/c/84253f3c2dad6be10d30c92626c763d9a9f512ad
• https://git.kernel.org/stable/c/9d448dd6bcb61a508204b57ea1f454ba9bac2f24
• https://git.kernel.org/stable/c/a100de2974d208cfca032179b02ed4d1a0a7f143
• https://git.kernel.org/stable/c/a240bc5c43130c6aa50831d7caaa02a1d84e1bce

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