CVE-2025-21636

Local service interruption via SCTP null dereference

Published Jan 19, 2025 · Updated May 11, 2026

NULL pointer dereference in the Linux kernel allows local users to interrupt service through an SCTP sysctl access during task exit. The plpmtud_probe_interval handler in net/sctp/sysctl.c obtains the network namespace through current->nsproxy even though that pointer can be NULL, instead of deriving it from table->data. A low-privileged local context and the task-exit condition are required; the resulting kernel Oops affects availability without reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel allows local users to interrupt service through an SCTP sysctl access during task exit. The plpmtud_probe_interval handler in net/sctp/sysctl.c obtains the network namespace through current->nsproxy even though that pointer can be NULL, instead of deriving it from table->data. A low-privileged local context and the task-exit condition are required; the resulting kernel Oops affects availability without reported data disclosure or modification.

The record

CVE
CVE-2025-21636
Published
Jan 19, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 19, 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=5.14
  2. Affected versionversion=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <1dc5da6c4178f3e4b95c631418f72de9f86c0449
  3. Affected versionversion=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <284a221f8fa503628432c7bb5108277c688c6ffa
  4. Affected versionversion=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <44ee8635922b6eb940faddb961a8347c6857d722
  5. Affected versionversion=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <6259d2484d0ceff42245d1f09cc8cb6ee72d847a
  6. Affected versionversion=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <bcf8c60074e81ed2ac2d35130917175a3949c917

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.14; version=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <1dc5da6c4178f3e4b95c631418f72de9f86c0449; version=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <284a221f8fa503628432c7bb5108277c688c6ffa; version=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <44ee8635922b6eb940faddb961a8347c6857d722; version=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <6259d2484d0ceff42245d1f09cc8cb6ee72d847a; version=d1e462a7a5f359cbb9a0e8fbfafcfb6657034105 <bcf8c60074e81ed2ac2d35130917175a3949c917

Published CVSS scores

5.5Canonical Ubuntu SecurityCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS: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.

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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

CWE-476NULL Pointer Dereference
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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