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CVE-2026-64600

xfs: resample the data fork mapping after cycling ILOCK

No known exploitation. EPSS puts it in the 39th percentile. Fixed versions are out.

CVSS 3.17.8HighEPSS percentile39th0.5% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFix1 product4 fixed builds listed below

Published Updated Sources: CVE.org, NVD

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • LinuxAffected: ≥ 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5, < dc11be133efca5fe3a2fb02b016dee825cc12f18Upgrade to: dc11be133efca5fe3a2fb02b016dee825cc12f18Affected: ≥ 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5, < b8c9aa832b52680ee40d6cab0efb081f9a69df05Upgrade to: b8c9aa832b52680ee40d6cab0efb081f9a69df05Affected: ≥ 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5, < 50f0012da1040f69a4e788cd9aed587c9a04983fUpgrade to: 50f0012da1040f69a4e788cd9aed587c9a04983fAffected: ≥ 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5, < e705d81a7193dd19e69b8e2bad4696d78a4ea075Upgrade to: e705d81a7193dd19e69b8e2bad4696d78a4ea075 + 3 more branchesStated by: CVE record

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

Coverage timeline

4 publishers

  1. Nine-year-old Linux XFS reflink race condition vulnerability discovered and patched as CVE-2026-64600.

    ·Хакер (xakep.ru) summary

  2. A nine-year-old privilege escalation flaw (CVE-2026-64600) in the Linux XFS filesystem allows local users to gain root access and is now patched.

    ·BleepingComputer summary

  3. Qualys discovered and disclosed a critical local privilege escalation flaw (CVE-2026-64600) in the Linux kernel's XFS filesystem.

    ·Qualys Security Blog summary

Sourced from public security reporting — each date is when it was published, not when it happened. 1 further article named this CVE in wider roundups without reporting it as a distinct event.

What it is

From the CVE record

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.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS39th
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.5% chance of exploitation activity in the next 30 days, which ranks it in the 39th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

20 events over 95 days, from the signal feeds we watch.

  1. Patch availablerecord updated
  2. Patch availablerecord updated
  3. Patch availablerecord updated
  4. Record updated
  5. Record updatedrecord updated
  6. Record updated

Affected products

And 1 more affected product. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Scored 7.8 by NVD.

How it is reached

  • Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 11 more references. See all after sign-in

In the news

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