CVE-2026-80996
Received Received - Intake

Linux Kernel L2TP Multicast Notification Error Handling

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net: l2tp: do not propagate multicast notification errors The tunnel create, tunnel modify, session create, and session modify netlink handlers send multicast notifications through helpers that can fail while allocating or encoding a message, or while multicasting it. For tunnel and session create/modify, a notification is sent after the live operation has completed. Returning a best-effort notification error as the command result can therefore report failure for an operation that already committed and can cause callers to retry and accumulate live objects. Keep sending notifications for listener visibility, but do not propagate their best-effort status as the command result. This also keeps the tunnel modify command consistent with the other notification-only paths.

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Meta Information

Published
2026-09-11
Last Modified
2026-09-11
Generated
2026-09-12
AI Q&A
2026-09-11
EPSS Evaluated
N/A
NVD
CVE-2026-80996
EUVD
EUVD-2026-76319

Affected Vendors & Products

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

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Exploitability

CWE
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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 multicast notification errors during tunnel and session operations in the L2TP (Layer 2 Tunneling Protocol) module. When creating or modifying tunnels and sessions, the system sends notifications to inform listeners about changes. If these notifications fail due to allocation, encoding, or multicasting issues, the operation may incorrectly report an error even though the actual operation succeeded. This can cause callers to retry unnecessarily, leading to accumulation of live objects.

Detection Guidance

This vulnerability affects the Linux kernel's L2TP netlink handlers. Detection requires checking kernel logs for errors related to L2TP tunnel or session modifications. Commands like dmesg | grep l2tp or journalctl -k | grep l2tp may help identify issues. Ensure your kernel version is updated to a patched release.

Impact Analysis

This vulnerability may cause system instability or resource exhaustion if callers repeatedly retry operations that have already succeeded. It could lead to unnecessary load on the system, potential performance degradation, or unexpected behavior in network services relying on L2TP tunnels and sessions.

Mitigation Strategies

Update the Linux kernel to the latest stable version that includes the fix for this vulnerability. Monitor kernel logs for L2TP-related errors and ensure no misconfigured tunnels or sessions exist. Restart affected services after updating.

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