CVE-2025-21768

Service interruption via self-cached lwtunnel reference

Published Feb 27, 2025 · Updated May 11, 2026

Memory leak in IPv6 lightweight tunnels in affected Linux kernel versions allows local users to exhaust memory and interrupt service. The RPL, SEG6, and IOAM6 destination caches can retain a reference to their own lwtunnel when packet transformation leaves the destination unchanged, so the lwtunnel state is never freed. Low-privileged local access is required; IOAM6 reproduced the leak, while reachability through RPL and SEG6 remains unconfirmed.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in IPv6 lightweight tunnels in affected Linux kernel versions allows local users to exhaust memory and interrupt service. The RPL, SEG6, and IOAM6 destination caches can retain a reference to their own lwtunnel when packet transformation leaves the destination unchanged, so the lwtunnel state is never freed. Low-privileged local access is required; IOAM6 reproduced the leak, while reachability through RPL and SEG6 remains unconfirmed.

The record

CVE
CVE-2025-21768
Published
Feb 27, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=4.10
  2. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <4c0f200c7d06fedddde82209c099014d63f4a6c0
  3. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <5ab11a4e219e93b8b31a27f8ec98d42afadd8b7a
  4. Affected versionversion=6c8702c60b88651072460f3f4026c7dfe2521d12 <92191dd1073088753821b862b791dcc83e558e07

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.10; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <4c0f200c7d06fedddde82209c099014d63f4a6c0; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <5ab11a4e219e93b8b31a27f8ec98d42afadd8b7a; version=6c8702c60b88651072460f3f4026c7dfe2521d12 <92191dd1073088753821b862b791dcc83e558e07

Published CVSS scores

5.5NIST National Vulnerability DatabaseCVSS: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-401Missing Release of Memory after Effective Lifetime
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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