Answer in brief
CVE-2026-63808 records a Critical severity (CVSS 9.8) vulnerability in exfat: fix potential use-after-free in exfat_find_dir_entry(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <e6f1a11cfb808441a43ffae9b476cc135732cd27 || >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <e48f413c2815787b8cade2795e194e3c4cd782ef || >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <06c4e1e9967d332ac33ba38b7819851089ff9359 || >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <8e0abc17fbd7e305802e84fe98b4950d50f9c433 || >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <4d101016d5e587f820b3ae2d5bb6770d86342649 || >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <adfacfbaeae2cb760f492357cc36b41f84ef7f86 || >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <708b97e792945d3e4653939fd3405d71a61ad065 || >=ca06197382bde0a3bc20215595d1c9ce20c6e341 <3f5f8ee9917cc2b9076ac533492d8a200edcabb8 | e6f1a11cfb808441a43ffae9b476cc135732cd27, e48f413c2815787b8cade2795e194e3c4cd782ef, 06c4e1e9967d332ac33ba38b7819851089ff9359, 8e0abc17fbd7e305802e84fe98b4950d50f9c433, 4d101016d5e587f820b3ae2d5bb6770d86342649, adfacfbaeae2cb760f492357cc36b41f84ef7f86, 708b97e792945d3e4653939fd3405d71a61ad065, 3f5f8ee9917cc2b9076ac533492d8a200edcabb8 |
| Linux/Linuxgeneric | 5.7 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 22, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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.
Quoted source text, attributed separately from HOL analysis.