CVE-2026-64431

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-25. a secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In the Linux kernel, the following vulnerability has been resolved:

ntfs: avoid calling post_write_mst_fixup() for invalid index_block

ntfs_icx_ib_sync_write() calls post_write_mst_fixup() when ntfs_ib_write() returns an error, intending to restore the buffer after a failed write.

However, ntfs_ib_write() returns an error immediately if pre_write_mst_fixup() validation fails. The caller, ntfs_icx_ib_sync_write(), interprets any error as a write failure requiring rollback. It does not differentiate between I/O errors and validation failures, and calls post_write_mst_fixup() anyway.

Since post_write_mst_fixup() assumes that the index_block contents is correct, it doesn't perform the boundary checks, which results in out-of-bounds memory access.

An attacker can craft a malicious NTFS image with:

  • large index_block.usa_ofs offset, pointing outside the ntfs_record
  • index_block.usa_count = 0, causing integer underflow
  • or index_block.usa_count larger than actual number of sectors in the
ntfs_record, causing out-of-bounds access

KASAN reports describing the memory corruption: ================================================================== BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup+0x19c/0x1d0 Read of size 2 at addr ffff8881586c9018 by task p/9428 Call Trace: dump_stack_lvl+0x100/0x190 print_report+0x139/0x4ad ? post_write_mst_fixup+0x19c/0x1d0 ? __virt_addr_valid+0x262/0x500 ? post_write_mst_fixup+0x19c/0x1d0 kasan_report+0xe4/0x1d0 ? post_write_mst_fixup+0x19c/0x1d0 post_write_mst_fixup+0x19c/0x1d0 ntfs_icx_ib_sync_write+0x179/0x220 ntfs_inode_sync_filename+0x83d/0x1080 __ntfs_write_inode+0x1049/0x1480 ntfs_file_fsync+0x131/0x9b0 ================================================================== BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup+0x1aa/0x1d0 Write of size 2 at addr ffff8881586c91fe by task p/9428 Call Trace: dump_stack_lvl+0x100/0x190 print_report+0x139/0x4ad ? post_write_mst_fixup+0x1aa/0x1d0 ? __virt_addr_valid+0x262/0x500 ? post_write_mst_fixup+0x1aa/0x1d0 kasan_report+0xe4/0x1d0 ? post_write_mst_fixup+0x1aa/0x1d0 post_write_mst_fixup+0x1aa/0x1d0 ntfs_icx_ib_sync_write+0x179/0x220 ntfs_inode_sync_filename+0x83d/0x1080 __ntfs_write_inode+0x1049/0x1480 ntfs_file_fsync+0x131/0x9b0 ==================================================================

Let's move the post_write_mst_fixup() call to ntfs_ib_write(). The ntfs_ib_write() function calls pre_write_mst_fixup() at the beginning. If the index_block contents is invalid, pre_write_mst_fixup() fails and ntfs_ib_write() returns early without calling post_write_mst_fixup() on bad index_block.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

July 25, 2026

Last Modified

August 17, 2026

Advisory Details (2)

Auto-updated Jul 27, 2026
No patch confirmed yet.
generic

ntfs: avoid calling post_write_mst_fixup() for invalid index_block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e2018628301a6d9f54e34b0cb417f1688c66df1d
generic

ntfs: avoid calling post_write_mst_fixup() for invalid index_block - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5b6eedd7cc2936f9238e852b553a1b326105bde8

Vendor Advisories for CVE-2026-64431(1)

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

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (156 versions)7.1.4-1—

Data Freshness Timeline

(refreshed 18× in last 7d / 111× 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 143 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-64431?
CVE-2026-64431 is a high vulnerability published on July 25, 2026. In the Linux kernel, the following vulnerability has been resolved: ntfs: avoid calling postwritemstfixup() for invalid indexblock ntfsicxibsyncwrite() calls postwritemstfixup() when ntfsib_write() returns an error, intending to restore the buffer after a failed write. However, ntfsibwrite()…
When was CVE-2026-64431 disclosed?
CVE-2026-64431 was first published in the National Vulnerability Database on July 25, 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-2026-64431 actively exploited?
CVE-2026-64431 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 97.6% of all scored CVEs.
What is the CVSS score of CVE-2026-64431?
CVE-2026-64431 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-64431?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64431, 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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