CVE-2025-38504

Availability loss via skipped zcrx reference release

Published Aug 16, 2025 · Updated May 11, 2026

Improper resource release in Linux kernel 6.15 through 6.15.6 allows local users to interrupt service through io_uring zero-copy receive. In io_pp_zc_destroy(), a misplaced WARN_ON_ONCE branch returns before percpu_ref_put() when allocated niovs remain, leaving the context reference unreleased. Reachability requires local low-privileged access and a teardown path with multiple page pools or another state in which niovs remain allocated.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper resource release in Linux kernel 6.15 through 6.15.6 allows local users to interrupt service through io_uring zero-copy receive. In io_pp_zc_destroy(), a misplaced WARN_ON_ONCE branch returns before percpu_ref_put() when allocated niovs remain, leaving the context reference unreleased. Reachability requires local low-privileged access and a teardown path with multiple page pools or another state in which niovs remain allocated.

The record

CVE
CVE-2025-38504
Published
Aug 16, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 16, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=34a3e60821ab9f335a58d43a88cccdbefdebdec3 <203817de269539c062724d97dfa5af3cdf77a3ec
  2. Affected versionversion=34a3e60821ab9f335a58d43a88cccdbefdebdec3 <ad9f1b5bed082b9c910e2a24bae0286a70846909
  3. Affected versionversion=6.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=34a3e60821ab9f335a58d43a88cccdbefdebdec3 <203817de269539c062724d97dfa5af3cdf77a3ec; version=34a3e60821ab9f335a58d43a88cccdbefdebdec3 <ad9f1b5bed082b9c910e2a24bae0286a70846909; version=6.15

Published CVSS scores

5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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