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CVE-2025-68768 Linux CVE debrief

A vulnerability in the Linux kernel has been resolved. The issue involves a deadlock on pernet_ops_rwsem caused by conntrack looping forever in nf_conntrack_cleanup_net_list(). This happens because nf_defrag_ipv6 loads before conntrack, causing its netns exit hooks to run after conntrack's. To fix this, all fragment queue SKBs are flushed during fqdir_pre_exit() to release conntrack references before conntrack cleanup runs.

Vendor
Linux
Product
Unknown
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-01-13
Original CVE updated
2026-06-19
Advisory published
2026-01-13
Advisory updated
2026-06-19

Who should care

Linux kernel users and administrators should be aware of this vulnerability and take necessary actions to update their kernels.

Technical summary

The Linux kernel vulnerability (CVE-2025-68768) is caused by a deadlock on pernet_ops_rwsem. This deadlock occurs due to conntrack looping in nf_conntrack_cleanup_net_list(). The problem arises from nf_defrag_ipv6 loading before conntrack, causing its netns exit hooks to run after conntrack's. The fix involves flushing all fragment queue SKBs during fqdir_pre_exit() and in timer expiry handlers when fqdir->dead is set.

Defensive priority

High

Recommended defensive actions

  • Update the Linux kernel to the latest version.
  • Flush all fragment queue SKBs during fqdir_pre_exit() to release conntrack references.
  • Flush the queues in timer expiry handlers when they discover fqdir->dead is set.

Evidence notes

The vulnerability was discovered in NIPA, and the fix was provided by flushing pending skbs in fqdir_pre_exit().

Sources and references

Verified primary and authoritative sources

  • CVE-2025-68768 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-68768

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2025-68768 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-68768

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/006a5035b495dec008805df249f92c22c89c3d2e

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/543555954b1ee8d1903a7020324efb41b0c97428

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/c70df25214ac9b32b53e18e6ae3b8f073ffa6903

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.