CVE-2026-63800

Use-after-free via post-release tracepoint access

Published Jul 19, 2026 · Updated Jul 19, 2026

Use-after-free in Linux Kernel pNFS allows local users with root access to read a freed layout header during layout updates. In pnfs_update_layout(), the NFS_LAYOUT_RETURN retry path drops lo's final reference through pnfs_put_layout_hdr() before trace_pnfs_update_layout() reads fields from lo. Root access is required to arm the tracepoint, no privilege boundary is crossed, and published upstream analysis characterizes the condition as unexploitable.

CVSS severity9.8
Critical
EPSS probability0.53%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel pNFS allows local users with root access to read a freed layout header during layout updates. In pnfs_update_layout(), the NFS_LAYOUT_RETURN retry path drops lo's final reference through pnfs_put_layout_hdr() before trace_pnfs_update_layout() reads fields from lo. Root access is required to arm the tracepoint, no privilege boundary is crossed, and published upstream analysis characterizes the condition as unexploitable.

The record

CVE
CVE-2026-63800
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=06f58dbc49a23c99e5c0f246879ed16667f7bf8f <4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98
  2. Affected versionversion=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <13e198a90ca4050f4bee8a3f23680389a6563ccc
  3. Affected versionversion=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <1f24b8302c77dcaf79c64c073877a3b9f4dd25d2
  4. Affected versionversion=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <200e7637f4d6a1342987045eea72641524f909dc
  5. Affected versionversion=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <2883ddd7542b4437a2ab4908fe2773f690e20889
  6. Affected versionversion=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <7e37e9b3e82ade881e1798e2f4fcc54aff7793c1
  7. Affected versionversion=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <9645aaf689aff57427ece3b9fa47d5b5399417f4
  8. Affected versionversion=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <9c0fb5c09ae5bd68dc0038692af8127029cb0385
  9. Affected versionversion=5.10.9 <5.10.260
  10. Affected versionversion=5.11
  11. Affected versionversion=5.4.91 <5.5
  12. Affected versionversion=aa2399f55eff4ec78330bb6fe55f9df53e5cae0c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linux Kernelversion=06f58dbc49a23c99e5c0f246879ed16667f7bf8f <4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98; version=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <13e198a90ca4050f4bee8a3f23680389a6563ccc; version=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <1f24b8302c77dcaf79c64c073877a3b9f4dd25d2; version=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <200e7637f4d6a1342987045eea72641524f909dc; version=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <2883ddd7542b4437a2ab4908fe2773f690e20889; version=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <7e37e9b3e82ade881e1798e2f4fcc54aff7793c1; version=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <9645aaf689aff57427ece3b9fa47d5b5399417f4; version=2c8d5fc37fe2384a9bdb6965443ab9224d46f704 <9c0fb5c09ae5bd68dc0038692af8127029cb0385; version=5.10.9 <5.10.260; version=5.11; version=5.4.91 <5.5; version=aa2399f55eff4ec78330bb6fe55f9df53e5cae0c

Published CVSS scores

9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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