TI-2026-45548 Aliases CVE-2026-63983 GHSA-rj36-qxvm-r8rm

net/sched: fix packet loop on netem when duplicate is on

LOW 22Published 2026-07-19 · Updated 2026-10-15

Key facts

Attack vector: —
Privileges required: —
User interaction: —
Attack complexity: —
Impact type: —
Confidentiality · integrity · availability: —
Fix status: Partial Red Hat: 5 without a fix

No CVSS vector from any source. Fix status from CNA and Red Hat.

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: fix packet loop on netem when duplicate is on When netem duplicates a packet it re-enqueues the copy at the root qdisc. If another netem sits in the tree the copy can be duplicated again, recursing until the stack or memory is exhausted. The original duplication guard temporarily zeroed q->duplicate around the re-enqueue, but that does not cover all cases because it is per-qdisc state shared across all concurrent enqueue paths and is not safe without additional locking. Use the skb tc_depth field introduced in an earlier patch: - increment it on the duplicate before re-enqueue - skip duplication for any skb whose tc_depth is already non-zero. This marks the packet itself rather than mutating qdisc state, therefore it is safe regardless of tree topology or concurrency.

Why it matters now

EPSS 0.00168 6th percentileScored 2026-11-07

Fix Partial Linux (Linux): 6.12.93, 6.18.57, 7.0.12 +1Red Hat: 5 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Linux	Linux	2.6.12 and later	6.12.93, 6.18.57, 7.0.12, 7.1	Patch available	CNA

Linux VendorLinux Affected 2.6.12 and later Fixed in 6.12.93, 6.18.57, 7.0.12, 7.1 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:o:linux:linux_kernel::::::::	—	—	Linux

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Fix · CNA Linux (Linux) Fixed in 6.12.93, 6.18.57, 7.0.12, 7.1

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux 10	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 6	Affected	No fix planned: Out of support scope
Red Hat Enterprise Linux 7	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 8	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 9	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2026-63983
2026-10-03 Alias added: GHSA-rj36-qxvm-r8rm
2026-10-16 Fix available: Linux/Linux@4ec3a8ca97394f17e73a4d8d4c79c1c78b322772, Linux/[email protected] · CNA
2026-10-16 1 new reference · CNA

References

Other 4

TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4

See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences