CVE-2026-64600

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-23. a secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
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: Elevated riskExposed: 0

A fix is available — apply it.

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

xfs: resample the data fork mapping after cycling ILOCK

xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapping. Unfortunately, these two helpers cycle the ILOCK to grab a transaction, which means that the mappings are stale as soon as we reacquire the ILOCK. Currently we refresh the cow fork mapping by re-calling xfs_find_trim_cow_extent, but we don't refresh the data fork mapping beforehand, which means that the xfs_bmap_trim_cow in that function queries the refcount btree about the wrong physical blocks and returns an inaccurate value in *shared.

If *shared is now false, the directio write proceeds with a stale data fork mapping. Fix this by querying the data fork mapping if the sequence counter changes across the ILOCK cycle.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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%
Exploitation40% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
39%
KEV
Not listed

Published

July 23, 2026

Last Modified

August 18, 2026

Advisory Details (10)

Auto-updated Jul 27, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

oss-security - Re: RefluXFS: LPE in the Linux kernel via XFS reflink race (CVE-2026-64600)

http://www.openwall.com/lists/oss-security/2026/07/22/18
generic🟡 PoC Available

oss-security - RefluXFS: LPE in the Linux kernel via XFS reflink race (CVE-2026-64600)

http://www.openwall.com/lists/oss-security/2026/07/22/14
generic

xfs: resample the data fork mapping after cycling ILOCK - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e705d81a7193dd19e69b8e2bad4696d78a4ea075
generic

xfs: resample the data fork mapping after cycling ILOCK - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/dc11be133efca5fe3a2fb02b016dee825cc12f18
generic

xfs: resample the data fork mapping after cycling ILOCK - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b8c9aa832b52680ee40d6cab0efb081f9a69df05
generic

xfs: resample the data fork mapping after cycling ILOCK - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/50f0012da1040f69a4e788cd9aed587c9a04983f
generic

xfs: resample the data fork mapping after cycling ILOCK - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/44f891bc088958399eec27f7604928694aa35581
generic

xfs: resample the data fork mapping after cycling ILOCK - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7
generic

xfs: resample the data fork mapping after cycling ILOCK - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/206c09b04dc5469c7ff14d8aceff2d47c88078d9
generic🟡 PoC Available
https://cdn2.qualys.com/advisory/2026/07/22/RefluXFS.txt

Vendor Advisories for CVE-2026-64600(14)

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

Patch Availability(15)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-gcp-edge (7.0.0-1011.11~24.04.1) @ noble2026-09-14ubuntu
ubuntulinux-tools-oem-7.0 (7.0.0-1013.13) @ resolute2026-09-14ubuntu
ubuntulinux-virtual-hwe-26.04-edge (7.0.0-31.31) @ resolute2026-09-14ubuntu
redhatkpatch-patch2026-07-29redhat
redhatkernel-0:4.18.0-372.202.1.el8_62026-07-17redhat
redhatkernel-0:4.18.0-477.154.1.el8_82026-07-17redhat
redhatkernel-0:5.14.0-284.182.1.el9_22026-07-16redhat
redhatkernel-0:6.12.0-55.89.1.el10_02026-07-16redhat
redhatkernel-0:5.14.0-427.138.1.el9_42026-07-16redhat
redhatkernel-0:5.14.0-570.128.1.el9_62026-07-16redhat
redhatkernel-0:4.18.0-305.198.1.el8_42026-07-15redhat
redhatkernel-0:5.14.0-687.26.1.el9_82026-07-14redhat
redhatkernel-0:4.18.0-553.144.1.el8_102026-07-14redhat
redhatkernel-0:6.12.0-211.34.1.el10_22026-07-14redhat
redhatkernel-rt-0:4.18.0-553.144.1.rt7.485.el8_102026-07-14redhat

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

(6 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 7.2~rc5-1~exp1 (500 versions)——
linux-6.16.1.106-3~deb11u1 ... 6.1.177-1~deb11u1 (22 versions)6.1.180-1~deb11u1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (55 versions)6.1.180-1—
linux-6.12—6.12.100-1~deb12u1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.95-1~bpo12+1 (30 versions)6.12.96-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (158 versions)7.1.4-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(9)

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 27× in last 7d / 132× 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 302 total refreshes for this CVE.

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

Publicly available exploits

(3 references)

Working exploit code is in the public domain (3 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoClitosmartin/CVE-2026-64600-Refluxfs-PoC
    First seen Jul 27, 2026

    A POC for the recently discovered Qualys bug on COW with XFS

    Open source ↗
  • GitHub PoCDebajyoti0-0/CVE-2026-64600
    First seen Jul 26, 2026

    A C-based Linux security utility for detecting, safely verifying (Proof of Concept), and mitigating CVE-2026-64600 (RefluXFS). It provides kernel vulnerability assessment, XFS reflink detection, a safe race-condition PoC, and layered mitigation using SystemTap and XFS hardening.

    Open source ↗
  • GitHub PoC0xBlackash/CVE-2026-64600
    First seen Jul 22, 2026

    CVE-2026-64600

    Open source ↗

Frequently asked(5)

What is CVE-2026-64600?
CVE-2026-64600 is a high vulnerability published on July 23, 2026. In the Linux kernel, the following vulnerability has been resolved: xfs: resample the data fork mapping after cycling ILOCK xfsreflinkfill{cowhole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapping. Unfortunately, these two helpers cycle the ILOCK to grab a…
When was CVE-2026-64600 disclosed?
CVE-2026-64600 was first published in the National Vulnerability Database on July 23, 2026, with the most recent update on August 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-64600 actively exploited?
CVE-2026-64600 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 60.9% of all scored CVEs.
What is the CVSS score of CVE-2026-64600?
CVE-2026-64600 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-64600?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64600, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-64600

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