CVE-2026-64600

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7%, top 50% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 6 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: 1%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
1%
EPSS %ILE
50%
KEV
Not listed

Published

July 23, 2026

Last Modified

July 27, 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(13)

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

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
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-0:5.14.0-570.128.1.el9_62026-07-16redhat
redhatkernel-0:5.14.0-427.138.1.el9_42026-07-16redhat
redhatkernel-0:6.12.0-55.89.1.el10_02026-07-16redhat
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.

Data Freshness Timeline

(refreshed 22× in last 7d / 22× 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.

  1. 2026-07-27 05:21 UTCEG score recompute▲ 7.80
  2. 2026-07-27 05:21 UTCVendor advisory
  3. 2026-07-27 05:20 UTCGHSA enrichment
  4. 2026-07-27 05:12 UTCMITRE cvelistV5CVSS v3 → 7.8 · severity → HIGH
  5. 2026-07-26 14:54 UTCEPSS rescore
  6. 2026-07-26 14:54 UTCEPSS rescore
  7. 2026-07-26 03:21 UTCEG score recompute
  8. 2026-07-26 03:21 UTCVendor advisory
  9. 2026-07-26 03:21 UTCGHSA enrichment
  10. 2026-07-25 14:18 UTCEPSS rescore
  11. 2026-07-25 14:18 UTCEPSS rescore
  12. 2026-07-24 16:11 UTCNVD update
  13. 2026-07-24 15:13 UTCMITRE cvelistV5
  14. 2026-07-24 14:18 UTCEPSS rescore
  15. 2026-07-24 14:18 UTCEPSS rescore
  16. 2026-07-24 08:11 UTCNVD update
  17. 2026-07-24 06:36 UTCMITRE cvelistV5
  18. 2026-07-23 14:18 UTCEPSS rescore
  19. 2026-07-23 14:18 UTCEPSS rescore
  20. 2026-07-23 09:52 UTCNVD update
  21. 2026-07-23 05:50 UTCEG score recompute
  22. 2026-07-23 05:49 UTCMITRE cvelistV5first tracked

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • 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 July 27, 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 1% probability of exploitation in the next 30 days, which ranks it in the top 49.8% 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

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