CVE-2026-63982
Received Received - Intake

Linux Kernel Net Sched Mirred Loop Vulnerability

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: Fix ethx:ingress -> ethy:egress -> ethx:ingress mirred loop When mirred redirects to ingress (from either ingress or egress) the loop state from sched_mirred_dev array dev is lost because of 1) the packet deferral into the backlog and 2) the fact the sched_mirred_dev array is cleared. In such cases, if there was a loop we won't discover it. Here's a simple test to reproduce: ip a add dev port0 10.10.10.11/24 tc qdisc add dev port0 clsact tc filter add dev port0 egress protocol ip \ prio 10 matchall action mirred ingress redirect dev port1 tc qdisc add dev port1 clsact tc filter add dev port1 ingress protocol ip \ prio 10 matchall action mirred egress redirect dev port0 ping -c 1 -W0.01 10.10.10.10

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-63982
EUVD
EUVD-2026-45755

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a loop issue in network traffic control (TC) when using mirred actions to redirect packets between ingress and egress queues. The loop state is lost due to packet deferral and clearing of the sched_mirred_dev array, allowing infinite packet loops between interfaces without detection.

Detection Guidance

The provided CVE data includes a test to reproduce the vulnerability using Linux networking commands. You can run the following commands to check for potential loop conditions in your system: ip a add dev port0 10.10.10.11/24; tc qdisc add dev port0 clsact; tc filter add dev port0 egress protocol ip prio 10 matchall action mirred ingress redirect dev port1; tc qdisc add dev port1 clsact; tc filter add dev port1 ingress protocol ip prio 10 matchall action mirred egress redirect dev port0; ping -c 1 -W0.01 10.10.10.10

Impact Analysis

This vulnerability can cause network performance degradation or outages due to infinite packet loops between network interfaces. It may lead to high CPU usage, bandwidth exhaustion, and potential denial-of-service conditions on affected systems.

Compliance Impact

This vulnerability in the Linux kernel involves a network packet redirection loop that could lead to denial-of-service conditions or unexpected network behavior. It does not directly relate to data privacy, access controls, or encryption mechanisms typically addressed by GDPR or HIPAA. Therefore, its impact on compliance with these standards is likely minimal or indirect.

Mitigation Strategies

Apply the latest Linux kernel updates to patch this vulnerability. If immediate patching is not possible, review and remove any misconfigured tc (traffic control) rules that may cause packet redirection loops between interfaces.

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