CVE-2026-63808exfat: fix potential use-after-free in exfat_find_dir_entry()
- 9.8CriticalCVSS base score
- 0.53%Exploitation in 30 daysEPSS · top 55% 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: exfat: fix potential use-after-free in exfat_find_dir_entry() In exfat_find_dir_entry(), the buffer_head obtained from exfat_get_dentry() is released with brelse(bh) before the fall-through TYPE_EXTEND branch reads the directory entry through ep (which points into bh->b_data): brelse(bh); if (entry_type == TYPE_EXTEND) { ... len = exfat_extract_uni_name(ep, entry_uniname); ... } After brelse() drops our reference, nothing guarantees that the underlying page backing bh->b_data remains valid for the subsequent exfat_extract_uni_name() read. This is the same pattern fixed in commit fc961522ddbd ("exfat: Fix potential use after free in exfat_load_upcase_table()"). Move brelse(bh) so it runs after ep is no longer dereferenced on each branch. Confirmed on QEMU x86_64 with CONFIG_KASAN=y + CONFIG_DEBUG_PAGEALLOC=y + CONFIG_PAGE_POISONING=y on linux-next, using a crafted exFAT image (long filename with same-hash collisions forcing the TYPE_EXTEND path). With a debug-only invalidate_bdev() inserted between brelse(bh) and the ep read to make the stale-deref window deterministic, the unpatched kernel faults: BUG: KASAN: use-after-free in exfat_find_dir_entry+0x133b/0x15a0 BUG: unable to handle page fault for address: ffff88801a5fa0c2 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI RIP: 0010:exfat_find_dir_entry+0x1188/0x15a0 With this patch applied, the same instrumented harness completes cleanly under the same sanitizer stack. I have not reproduced a crash on an uninstrumented kernel under ordinary reclaim; the instrumented A/B establishes the lifetime violation and that the patch closes it, not an unaided triggerability claim.
Timeline
ID reserved
By Linux
Published
- 3 months later
· 3 months 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 |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.53% · top 55% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < e6f1a11cfb808441a43ffae9b476cc135732cd27
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < e48f413c2815787b8cade2795e194e3c4cd782ef
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < 06c4e1e9967d332ac33ba38b7819851089ff9359
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < 8e0abc17fbd7e305802e84fe98b4950d50f9c433
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < 4d101016d5e587f820b3ae2d5bb6770d86342649
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < adfacfbaeae2cb760f492357cc36b41f84ef7f86
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < 708b97e792945d3e4653939fd3405d71a61ad065
- affected ca06197382bde0a3bc20215595d1c9ce20c6e341 – < 3f5f8ee9917cc2b9076ac533492d8a200edcabb8
- affected 5.7
- unaffected < 5.7
- unaffected 5.10.260 – ≤ 5.10.*
- unaffected 5.15.211 – ≤ 5.15.*
- unaffected 6.1.177 – ≤ 6.1.*
- unaffected 6.6.144 – ≤ 6.6.*
- unaffected 6.12.95 – ≤ 6.12.*
- unaffected 6.18.38 – ≤ 6.18.*
- unaffected 7.1.3 – ≤ 7.1.*
- unaffected 7.2 – ≤ *
References
References8
- https://git.kernel.org/stable/c/e6f1a11cfb808441a43ffae9b476cc135732cd27 (opens in a new tab)
- https://git.kernel.org/stable/c/e48f413c2815787b8cade2795e194e3c4cd782ef (opens in a new tab)
- https://git.kernel.org/stable/c/06c4e1e9967d332ac33ba38b7819851089ff9359 (opens in a new tab)
- https://git.kernel.org/stable/c/8e0abc17fbd7e305802e84fe98b4950d50f9c433 (opens in a new tab)
- https://git.kernel.org/stable/c/4d101016d5e587f820b3ae2d5bb6770d86342649 (opens in a new tab)
- https://git.kernel.org/stable/c/adfacfbaeae2cb760f492357cc36b41f84ef7f86 (opens in a new tab)
- https://git.kernel.org/stable/c/708b97e792945d3e4653939fd3405d71a61ad065 (opens in a new tab)
- https://git.kernel.org/stable/c/3f5f8ee9917cc2b9076ac533492d8a200edcabb8 (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-2026-45474 (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-2026-63808)Record last updated .