CVE-2025-21884

Local privilege escalation via kernel socket use-after-free

Published Mar 27, 2025 · Updated Aug 5, 2026

Use-after-free in affected Linux kernel branches allows local users to gain kernel privileges during network namespace teardown. Kernel sockets can retain a dangling network-namespace pointer because queued transmit packets delay socket freeing after the namespace reference is dropped. An unprivileged account with enabled user namespaces can groom the freed object, causing kernel memory disclosure, corruption, privilege escalation, or a crash.

CVSS severity7.8
High
EPSS probability0.21%
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 affected Linux kernel branches allows local users to gain kernel privileges during network namespace teardown. Kernel sockets can retain a dangling network-namespace pointer because queued transmit packets delay socket freeing after the namespace reference is dropped. An unprivileged account with enabled user namespaces can groom the freed object, causing kernel memory disclosure, corruption, privilege escalation, or a crash.

The record

CVE
CVE-2025-21884
Published
Mar 27, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 27, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=0cafd77dcd032d1687efaba5598cf07bce85997f <2668e038800b946d269f96ec1b258c01930a242c
  2. Affected versionversion=0cafd77dcd032d1687efaba5598cf07bce85997f <4ceb0bd4ffd009821b585ce6a8033b12b59fb5fb
  3. Affected versionversion=0cafd77dcd032d1687efaba5598cf07bce85997f <5c70eb5c593d64d93b178905da215a9fd288a4b5
  4. Affected versionversion=0cafd77dcd032d1687efaba5598cf07bce85997f <c31a732fac46b00b95b78fcc9c37cb48dd6f2e0c
  5. Affected versionversion=6.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0cafd77dcd032d1687efaba5598cf07bce85997f <2668e038800b946d269f96ec1b258c01930a242c; version=0cafd77dcd032d1687efaba5598cf07bce85997f <4ceb0bd4ffd009821b585ce6a8033b12b59fb5fb; version=0cafd77dcd032d1687efaba5598cf07bce85997f <5c70eb5c593d64d93b178905da215a9fd288a4b5; version=0cafd77dcd032d1687efaba5598cf07bce85997f <c31a732fac46b00b95b78fcc9c37cb48dd6f2e0c; version=6.2

Published CVSS scores

7.8LinuxCVSS:3.1/AV:L/AC:L/PR:L/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 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

T1068Exploitation for Privilege Escalation

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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