CVE-2026-31702f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()
- 7.8HighCVSS base score
- 0.12%Exploitation in 30 daysEPSS · top 98% 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: f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io() In f2fs_compress_write_end_io(), dec_page_count(sbi, type) can bring the F2FS_WB_CP_DATA counter to zero, unblocking f2fs_wait_on_all_pages() in f2fs_put_super() on a concurrent unmount CPU. The unmount path then proceeds to call f2fs_destroy_page_array_cache(sbi), which destroys sbi->page_array_slab via kmem_cache_destroy(), and eventually kfree(sbi). Meanwhile, the bio completion callback is still executing: when it reaches page_array_free(sbi, ...), it dereferences sbi->page_array_slab — a destroyed slab cache — to call kmem_cache_free(), causing a use-after-free. This is the same class of bug as CVE-2026-23234 (which fixed the equivalent race in f2fs_write_end_io() in data.c), but in the compressed writeback completion path that was not covered by that fix. Fix this by moving dec_page_count() to after page_array_free(), so that all sbi accesses complete before the counter decrement that can unblock unmount. For non-last folios (where atomic_dec_return on cic->pending_pages is nonzero), dec_page_count is called immediately before returning — page_array_free is not reached on this path, so there is no post-decrement sbi access. For the last folio, page_array_free runs while the F2FS_WB_CP_DATA counter is still nonzero (this folio has not yet decremented it), keeping sbi alive, and dec_page_count runs as the final operation.
Timeline
ID reserved
By Linux
- 53 days later
· 53 days later
Published
- 44 days later
· 44 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
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 – < 57bc678f36ac03281e877c6b84877b43f964143f
- affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 – < ef57cd3329b40c739b9a2e1a8a21ecc4171c6280
- affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 – < f5154cf3ce1c8193f0c1891d3769f62740cfe6fe
- affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 – < c76cf339b87975ae5b2c06d2d774d5667d25a12a
- affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 – < 2c97dcb6147c8f7f25c629b93be1e69617de5d4a
- affected 4c8ff7095bef64fc47e996a938f7d57f9e077da3 – < 39d4ee19c1e7d753dd655aebee632271b171f43a
- affected 5.6
- unaffected < 5.6
- unaffected 6.1.175 – ≤ 6.1.*
- unaffected 6.6.136 – ≤ 6.6.*
- unaffected 6.12.84 – ≤ 6.12.*
- unaffected 6.18.25 – ≤ 6.18.*
- unaffected 7.0.2 – ≤ 7.0.*
- unaffected 7.1 – ≤ *
References
References6
- https://git.kernel.org/stable/c/57bc678f36ac03281e877c6b84877b43f964143f (opens in a new tab)
- https://git.kernel.org/stable/c/ef57cd3329b40c739b9a2e1a8a21ecc4171c6280 (opens in a new tab)
- https://git.kernel.org/stable/c/f5154cf3ce1c8193f0c1891d3769f62740cfe6fe (opens in a new tab)
- https://git.kernel.org/stable/c/c76cf339b87975ae5b2c06d2d774d5667d25a12a (opens in a new tab)
- https://git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4a (opens in a new tab)
- https://git.kernel.org/stable/c/39d4ee19c1e7d753dd655aebee632271b171f43a (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-2026-26511 (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)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-31702)Record last updated .