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Vulnerabilities

Vulnerability · CVE-2025-21768

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels Some lwtunnels have a dst cache for p…

Published Feb 27, 2025 · catalog updated Oct 21, 2026 · linux kernel

Check if you run it

No confirmed exploitation is on record for CVE-2025-21768. EPSS is 0.21%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.21%
Remediation
Version ranges on file
Affected products
cpe linux/linux kernel

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels Some lwtunnels have a dst cache for post-transformation dst. If the packet destination did not change we may end up recording a reference to the lwtunnel in its own cache, and the lwtunnel state will never be freed. Discovered by the ioam6.sh test, kmemleak was recently fixed to catch per-cpu memory leaks. I'm not sure if rpl and seg6 can actually hit this, but in principle I don't see why not.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe linux/linux kernel6.14
  • cpe linux/linux kernel< 6.12.16
  • cpe linux/linux kernel< 6.13.4

How to fix CVE-2025-21768

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-21768. EPSS is 0.21%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with linux/linux kernel 6.14; linux/linux kernel < 6.12.16; linux/linux kernel < 6.13.4. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-401: Missing Release of Memory after Effective Lifetime. EPSS 0.21%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 27, 2025 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels Some lwtunnels have a dst cache for post-transformation dst. If the packet destination did not change we may end up recording a reference to the lwtunnel in its own cache, and the lwtunnel state will never be freed. Discovered by the ioam6.sh test, kmemleak was recently

  2. Oct 21, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels Some lwtunnels have a dst cache for post-transformation dst. If the packet destination did not change we may end up recording a reference to the lwtunnel in its own cache, and the lwtunnel state will never be freed. Discovered by the ioam6.sh test, kmemleak was recently

Sources

  • CVE.orgVulnerability recordCVE-2025-21768

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-21768

    30-day exploitation probability 0.21%

    first.org
  • NIST NVDVulnerability recordCVE-2025-21768

    In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels Some lwtunnels have a dst cache for post-transformation dst. If the packet destination did not change we may end up recording a reference to the lwt

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.