CVE-2026-63808

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-19. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
44%
KEV
Not listed

Published

July 19, 2026

Last Modified

August 17, 2026

Advisory Details (8)

Auto-updated Sep 14, 2026
No patch confirmed yet.
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e6f1a11cfb808441a43ffae9b476cc135732cd27
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e48f413c2815787b8cade2795e194e3c4cd782ef
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/adfacfbaeae2cb760f492357cc36b41f84ef7f86
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8e0abc17fbd7e305802e84fe98b4950d50f9c433
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/708b97e792945d3e4653939fd3405d71a61ad065
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4d101016d5e587f820b3ae2d5bb6770d86342649
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3f5f8ee9917cc2b9076ac533492d8a200edcabb8
generic

exfat: fix potential use-after-free in exfat_find_dir_entry() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/06c4e1e9967d332ac33ba38b7819851089ff9359

Vendor Advisories for CVE-2026-63808(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-gcp-edge (7.0.0-1011.11~24.04.1) @ noble2026-09-18ubuntu
ubuntulinux-tools-nvidia-hwe-24.04-edge (7.0.0-1018.18~24.04.1) @ noble2026-09-18ubuntu
ubuntulinux-virtual-hwe-26.04-edge (7.0.0-31.31) @ resolute2026-09-18ubuntu
ubuntulinux-tools-oem-7.0 (7.0.0-1013.13) @ resolute2026-09-18ubuntu
redhatkernel-0:6.12.0-211.51.1.el10_22026-09-04redhat
redhatkernel-0:5.14.0-687.44.1.el9_82026-09-04redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (55 versions)5.10.262-1—
linux-6.16.1.106-3~deb11u1 ... 6.1.176-1~deb11u1 (21 versions)6.1.177-1~deb11u1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (54 versions)6.1.177-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.95-1~bpo12+1 (29 versions)6.12.95-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (156 versions)7.1.3-1—

Additional Vendor Advisories

(4)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 33× in last 7d / 129× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 336 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 09:49 UTCVendor advisory
  3. 2026-09-18 09:49 UTCGHSA enrichment
  4. 2026-09-18 04:27 UTCEG score recompute
  5. 2026-09-18 04:27 UTCVendor advisory
  6. 2026-09-18 04:27 UTCGHSA enrichment
  7. 2026-09-17 10:06 UTCEG score recompute
  8. 2026-09-17 10:06 UTCVendor advisory
  9. 2026-09-17 10:06 UTCGHSA enrichment
  10. 2026-09-16 14:08 UTCEPSS rescore
  11. 2026-09-16 05:15 UTCEPSS rescore
  12. 2026-09-14 12:18 UTCVendor advisory
  13. 2026-09-14 12:18 UTCGHSA enrichment
  14. 2026-09-14 07:44 UTCVendor advisory
  15. 2026-09-14 07:44 UTCGHSA enrichment
  16. 2026-09-14 03:22 UTCVendor advisory
  17. 2026-09-14 03:22 UTCGHSA enrichment
  18. 2026-09-13 23:01 UTCVendor advisory
  19. 2026-09-13 23:00 UTCGHSA enrichment
  20. 2026-09-13 17:05 UTCEG score recompute
  21. 2026-09-13 17:05 UTCVendor advisory
  22. 2026-09-13 17:05 UTCGHSA enrichment
  23. 2026-09-13 12:39 UTCVendor advisory
  24. 2026-09-13 12:39 UTCGHSA enrichment
  25. 2026-09-13 08:16 UTCVendor advisory
Show 75 more
  1. 2026-09-13 08:16 UTCGHSA enrichment
  2. 2026-09-13 03:55 UTCVendor advisory
  3. 2026-09-13 03:55 UTCGHSA enrichment
  4. 2026-09-12 16:57 UTCEG score recompute
  5. 2026-09-12 16:57 UTCVendor advisory
  6. 2026-09-12 16:57 UTCGHSA enrichment
  7. 2026-09-12 12:35 UTCVendor advisory
  8. 2026-09-12 12:35 UTCGHSA enrichment
  9. 2026-09-12 07:22 UTCVendor advisory
  10. 2026-09-12 07:22 UTCGHSA enrichment
  11. 2026-09-12 01:09 UTCVendor advisory
  12. 2026-09-12 01:09 UTCGHSA enrichment
  13. 2026-09-11 20:33 UTCEG score recompute
  14. 2026-09-11 20:33 UTCVendor advisory
  15. 2026-09-11 20:32 UTCGHSA enrichment
  16. 2026-09-11 14:53 UTCEPSS rescore
  17. 2026-09-11 09:37 UTCEPSS rescore
  18. 2026-09-08 22:01 UTCEPSS rescore
  19. 2026-09-07 23:45 UTCEG score recompute
  20. 2026-09-07 23:45 UTCVendor advisory
  21. 2026-09-07 23:45 UTCGHSA enrichment
  22. 2026-09-07 16:01 UTCEPSS rescore
  23. 2026-09-06 17:38 UTCEG score recompute
  24. 2026-09-06 17:38 UTCVendor advisory
  25. 2026-09-06 17:38 UTCGHSA enrichment
  26. 2026-09-06 13:47 UTCEPSS rescore
  27. 2026-09-06 13:16 UTCVendor advisory
  28. 2026-09-06 13:16 UTCGHSA enrichment
  29. 2026-09-06 05:00 UTCVendor advisory
  30. 2026-09-06 05:00 UTCGHSA enrichment
  31. 2026-09-06 00:38 UTCVendor advisory
  32. 2026-09-06 00:38 UTCGHSA enrichment
  33. 2026-09-05 20:16 UTCEG score recompute
  34. 2026-09-05 20:16 UTCVendor advisory
  35. 2026-09-05 20:16 UTCGHSA enrichment
  36. 2026-09-05 15:31 UTCEPSS rescore
  37. 2026-09-04 05:07 UTCEPSS rescore
  38. 2026-09-02 14:12 UTCEPSS rescore
  39. 2026-09-01 13:54 UTCEPSS rescore
  40. 2026-09-01 04:40 UTCEPSS rescore
  41. 2026-08-31 05:42 UTCGHSA enrichment
  42. 2026-08-31 01:20 UTCGHSA enrichment
  43. 2026-08-30 20:59 UTCEG score recompute
  44. 2026-08-30 20:59 UTCGHSA enrichment
  45. 2026-08-30 19:17 UTCEPSS rescore
  46. 2026-08-30 16:37 UTCGHSA enrichment
  47. 2026-08-30 12:15 UTCGHSA enrichment
  48. 2026-08-30 07:27 UTCGHSA enrichment
  49. 2026-08-30 03:03 UTCEG score recompute
  50. 2026-08-30 03:03 UTCGHSA enrichment
  51. 2026-08-30 01:22 UTCEPSS rescore
  52. 2026-08-28 21:42 UTCEPSS rescore
  53. 2026-08-28 01:47 UTCGHSA enrichment
  54. 2026-08-27 21:25 UTCEG score recompute
  55. 2026-08-27 21:25 UTCGHSA enrichment
  56. 2026-08-27 14:25 UTCEPSS rescore
  57. 2026-08-27 11:58 UTCGHSA enrichment
  58. 2026-08-27 02:50 UTCGHSA enrichment
  59. 2026-08-26 22:29 UTCEG score recompute
  60. 2026-08-26 22:29 UTCGHSA enrichment
  61. 2026-08-26 14:46 UTCEPSS rescore
  62. 2026-08-26 13:42 UTCGHSA enrichment
  63. 2026-08-26 08:59 UTCGHSA enrichment
  64. 2026-08-26 04:33 UTCGHSA enrichment
  65. 2026-08-25 23:46 UTCGHSA enrichment
  66. 2026-08-25 18:49 UTCEG score recompute
  67. 2026-08-25 18:49 UTCGHSA enrichment
  68. 2026-08-25 13:49 UTCEPSS rescore
  69. 2026-08-25 13:02 UTCGHSA enrichment
  70. 2026-08-25 08:39 UTCGHSA enrichment
  71. 2026-08-25 03:54 UTCGHSA enrichment
  72. 2026-08-24 23:32 UTCGHSA enrichment
  73. 2026-08-24 19:11 UTCEG score recompute
  74. 2026-08-24 19:11 UTCGHSA enrichment
  75. 2026-08-24 13:34 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-63808?
CVE-2026-63808 is a critical vulnerability published on July 19, 2026. In the Linux kernel, the following vulnerability has been resolved: exfat: fix potential use-after-free in exfatfinddir_entry() In exfatfinddirentry(), the bufferhead obtained from exfatgetdentry() is released with brelse(bh) before the fall-through TYPE_EXTEND branch reads the directory entry…
When was CVE-2026-63808 disclosed?
CVE-2026-63808 was first published in the National Vulnerability Database on July 19, 2026, with the most recent update on August 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63808 actively exploited?
CVE-2026-63808 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 56.4% of all scored CVEs.
What is the CVSS score of CVE-2026-63808?
CVE-2026-63808 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-63808?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63808, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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