CVE-2026-92503ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()
- —Not scoredno CVSS score yet
- 0.22%Exploitation in 30 daysEPSS · top 87% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find() Syzbot/stress-ng reported an ABBA deadlock in ext4 when exercising concurrent xattr workloads (using the ea_inode mount/format option). The deadlock occurs between the running transaction and the eviction thread: - Task 1 (stress-ng): Holds a reference to a shared mbcache_entry (ce) and calls ext4_xattr_inode_cache_find() -> ext4_iget() to retrieve the corresponding EA inode. Since the EA inode is currently being evicted, ext4_iget() blocks in __wait_on_freeing_inode() waiting for eviction to complete. - Task 2 (eviction thread): Currently evicting the same EA inode in ext4_evict_ea_inode(). It calls mb_cache_entry_wait_unused(oe) which blocks waiting for Task 1 to release the reference to the mbcache_entry. To break this deadlock, implement a new ext4_iget() configuration flag named EXT4_IGET_NOWAIT. When set, perform a non-blocking lookup of the inode via VFS's find_inode_nowait() API. If the inode is currently being evicted (marked with I_FREEING or I_WILL_FREE) or created (I_CREATING), or if it is not present in the VFS inode cache (cache miss), simply skip it (returning -ENOENT) rather than waiting for eviction/creation to complete, breaking the ABBA cycle. Since we return -ENOENT immediately on a cache miss, we never attempt to allocate a new inode or call iget_locked(), completely eliminating any TOCTOU race window. If the returned inode is I_NEW, wait for its initialization to clear via wait_on_new_inode(). If initialization fails and the inode is unhashed during wait_on_new_inode() waking up (e.g., due to an I/O read error in another thread), safely drop the reference and return -ENOENT. This unhashed check is executed unconditionally on all cache-hit pathways to properly handle concurrent initialization failures. Finally, standard validation checks (including is_bad_inode, EXT4_EA_INODE_FL, file_acl, and xattr flags) are executed as normal inside check_igot_inode() to fully guarantee VFS-layer safety. In ext4_xattr_inode_cache_find(), invoke ext4_iget() with the new EXT4_IGET_NOWAIT flag to perform the non-blocking cache search.
Timeline
ID reserved
By Linux
- 1 day later
· 1 day later
Published
- 43 days later
· 43 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.22% · top 87% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 0752e7fb549d90c33b4d4186f11cfd25a556d1dd – < e5e883ffe5230320060ea613a1acf750f3161c95
- affected 737fb7853acd5bc8984f6f42e4bfba3334be8ae1 – < 29a2a166450a3e89f61a486033b10cf170fde8b0
- affected 0a46ef234756dca04623b7591e8ebb3440622f0b – < d3b19b318e0e0483180d15f1d9f5e807a1fb59d5
- affected 0a46ef234756dca04623b7591e8ebb3440622f0b – < 074d0620401974cbfa9b63684cdfae99c7b2059c
- affected 0a46ef234756dca04623b7591e8ebb3440622f0b – < 7720fddd1fe344d14be258a2028f74ebf1569511
- affected 0a46ef234756dca04623b7591e8ebb3440622f0b – < 03438084a7b8621fb5c762dd3d04cff5f2630fb2
- affected 111103907234bffd0a34fba070ad9367de058752
- affected 6.1.107 – < 6.1.191
- affected 6.6.47 – < 6.6.160
- affected 6.9.7 – < 6.10
- affected 6.10
- unaffected < 6.10
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.160 – ≤ 6.6.*
- unaffected 6.12.114 – ≤ 6.12.*
- unaffected 6.18.57 – ≤ 6.18.*
- unaffected 7.2.6 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References6
- https://git.kernel.org/stable/c/e5e883ffe5230320060ea613a1acf750f3161c95 (opens in a new tab)
- https://git.kernel.org/stable/c/29a2a166450a3e89f61a486033b10cf170fde8b0 (opens in a new tab)
- https://git.kernel.org/stable/c/d3b19b318e0e0483180d15f1d9f5e807a1fb59d5 (opens in a new tab)
- https://git.kernel.org/stable/c/074d0620401974cbfa9b63684cdfae99c7b2059c (opens in a new tab)
- https://git.kernel.org/stable/c/7720fddd1fe344d14be258a2028f74ebf1569511 (opens in a new tab)
- https://git.kernel.org/stable/c/03438084a7b8621fb5c762dd3d04cff5f2630fb2 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-82124 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-92503)Record last updated .