CVE-2026-63795Network attack vector

Kernel memory corruption via premature oldfid release

Published Jul 19, 2026 · Updated Jul 19, 2026

Use-after-free in the Linux kernel 9p client allows remote attackers to crash systems through a malicious mounted 9p server. The p9_client_walk() clunk_fid error path unconditionally calls p9_fid_put(fid) after a failed non-cloning walk even when fid aliases caller-owned oldfid, prematurely destroying the shared object. Reachability requires an existing 9p mount, a split multi-component walk, and a crafted failure during a later segment; reuse can expose or corrupt kernel memory, escalate privileges, or panic the kernel.

CVSS severity10.0
Critical
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel 9p client allows remote attackers to crash systems through a malicious mounted 9p server. The p9_client_walk() clunk_fid error path unconditionally calls p9_fid_put(fid) after a failed non-cloning walk even when fid aliases caller-owned oldfid, prematurely destroying the shared object. Reachability requires an existing 9p mount, a split multi-component walk, and a crafted failure during a later segment; reuse can expose or corrupt kernel memory, escalate privileges, or panic the kernel.

The record

CVE
CVE-2026-63795
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1203
Attack vector
network
Privileges
unauthenticated

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=6.0
  2. Affected versionversion=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <1a3860d46e3eb47dbd60339783cdad7904486b9f
  3. Affected versionversion=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <6dbe9443d9f5f7fb6d319a7b77108853ae6c6bea
  4. Affected versionversion=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <99c379ca1e221c3d75c7c804ebbf4e5ee37a3070
  5. Affected versionversion=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <a61bdcba4f64c2f90d01461913f429ab151f1ca6
  6. Affected versionversion=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <a7656d368265d085ac9bb85ab31b0cdb72ad8c38
  7. Affected versionversion=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <b84f46179c806450b89821221ea5bd9a1698aba8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.0; version=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <1a3860d46e3eb47dbd60339783cdad7904486b9f; version=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <6dbe9443d9f5f7fb6d319a7b77108853ae6c6bea; version=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <99c379ca1e221c3d75c7c804ebbf4e5ee37a3070; version=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <a61bdcba4f64c2f90d01461913f429ab151f1ca6; version=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <a7656d368265d085ac9bb85ab31b0cdb72ad8c38; version=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <b84f46179c806450b89821221ea5bd9a1698aba8

Published CVSS scores

10.0LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1203Exploitation for Client Execution

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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