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Dossier · Vulnerability

Vulnerability · NVD published 2026-07-23

CVE-2026-64600

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.

Signals

Exploited in the wild
Not on KEVNot in CISA's catalogue as of the last daily pull. Absence is not proof of safety.
EPSS · 30-day forecast
0%Chance of exploitation in the next 30 days, 39th percentile of all CVEs. A forecast; KEV outranks it.
CVSS · NVD · HIGH
7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Internet exposure
not stated by sourcesNo exposure census on this CVE's dispatches.

Exploits

10 known · links only

GitHub PoCs · by trust, then stars10

  1. 0xBlackash/CVE-2026-64600 ↗Trust ok 100

    CVE-2026-64600

    ★ 21 · created 2026-07-22

  2. Debajyoti0-0/CVE-2026-64600 ↗Trust ok 100

    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.

    ★ 7 · created 2026-07-26

  3. litosmartin/CVE-2026-64600-Refluxfs-PoC ↗Trust ok 100

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

    ★ 4 · created 2026-07-27

  4. masrikky/CVE-2026-64600-RefluXFS ↗Trust ok 100

    A Linux kernel local privilege escalation affecting the XFS filesystem copy-on-write (CoW) path.

    ★ 1 · created 2026-08-08

  5. 0xSec1/CVE-2026-64600-RefluXFS-PoC ↗Trust ok 100

    PoC for RefluXFS

    ★ 0 · created 2026-08-14

  6. bha-vin/CVE-2026-64600-Exploit ↗Trust ok 100

    ★ 0 · created 2026-07-28

  7. HORKimhab/CVE-2026-64600 ↗Trust ok 100

    CVE-2026-64600 - Draft - Check todo

    ★ 0 · created 2026-07-23

  8. k4ntux/COWSlip ↗Trust ok 100

    xfs kernel LPE (CVE-2026-64600), disclosed by Qualys on 22 July 2026

    ★ 0 · created 2026-09-26

  9. letsr00t/RefluxFS_CVE-2026-64600 ↗Trust ok 100

    ★ 0 · created 2026-07-28

  10. vulnquest58/VQ-RefluxCore ↗Trust ok 100

    is an advanced security research framework designed to model, analyze, and demonstrate Local Privilege Escalation (LPE) mechanics associated with kernel-level race conditions and filesystem structure vulnerabilities (CVE-2026-64600 / RefluXFS)

    ★ 0 · created 2026-07-24

Fake proof-of-concept repositories have been used to deliver malware to the researchers who run them. The trust verdict is our engine's heuristic over the repository (account age, what it ships, how its stars arrived); it is a reason to read the code first, not a finding about its author.

On the wire

1 dispatch
  1. RefluXFS: A Linux Kernel Local Privilege Escalation to Root in XFS (CVE-2026-64600)VULN

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