CVE Catalog

CVE-2026-64207

MediumCVSS 5.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.11%

2th percentile - higher than 2% of all known CVEs

Summary

In the Linux kernel, a bug in DualPI2 (net/sched) GSO segmentation accounting causes double counting in the parent queue. When QFQ is the parent, after all real packets are dequeued, the queue still has non-zero length, leading to a NULL pointer dereference.

Risk Assessment

An attacker can trigger a kernel panic (NULL pointer dereference) causing denial of service (DoS) on systems using DualPI2 with QFQ as the parent qdisc.

Recommendation

Update the Linux kernel to a version containing the fix (commit: 5a8c3f5e4b2c). If not possible, avoid using DualPI2 with QFQ as the parent qdisc as a temporary workaround.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: net/sched: dualpi2: fix GSO backlog accounting When DualPI2 splits a GSO skb into N segments, it propagates N additional packets to its parent before returning NET_XMIT_SUCCESS. The parent then accounts for the original skb once more, leaving its qlen one larger than the number of packets actually queued. With QFQ as the parent, after all real packets are dequeued, QFQ still has a non-zero qlen while its in-service aggregate has no active classes. qfq_choose_next_agg() returns NULL and qfq_dequeue() passes the result to qfq_peek_skb(), causing a NULL pointer dereference. Follow the same pattern used by tbf_segment() and taprio: count only successfully queued segments, propagate the difference between the original skb and those segments, and return NET_XMIT_SUCCESS whenever at least one segment was queued.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS