CVE-2026-64093
Received Received - Intake

Timer Shutdown Race Condition in batman-adv tp_meter

Vulnerability report for CVE-2026-64093, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

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: batman-adv: tp_meter: directly shut down timer on cleanup batadv_tp_sender_cleanup() was calling timer_delete_sync() followed by timer_delete() to guard against the timer handler re-arming itself between the two calls. This double-deletion hack relied on the sending status being set to 0 to suppress re-arming. Replace both calls with a single timer_shutdown_sync(). This function both waits for any running timer callback to complete (like timer_delete_sync()) and permanently disarms the timer so it cannot be re-armed afterwards, making re-arming prevention unconditional and self-documenting. The re-arming property is also required because otherwise: 1. context 0 (batadv_tp_recv_ack()) checks in batadv_tp_reset_sender_timer() if sending is still 1 -> it is 2. context 1 changes in batadv_tp_sender_shutdown() sending to 0 and in this process forces the kthread to stop timer in batadv_tp_sender_cleanup() 3. context 0 continues in batadv_tp_reset_sender_timer() and rearms the timer -> but the reference for it is already gone

CVSS Scores

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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
EUVD

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability in the batman-adv module's tp_meter component. It involves a timer management issue where batadv_tp_sender_cleanup() improperly handled timer deletion, risking a race condition that could lead to timer re-arming after cleanup. The fix replaces double timer deletion with a single timer_shutdown_sync() call to prevent re-arming.

Detection Guidance

This vulnerability is specific to the Linux kernel's batman-adv module and does not have a direct detection method via network commands. It requires checking the kernel version and batman-adv module for the affected code paths. Inspect the kernel logs for timer-related errors in batman-adv or use kernel debugging tools to verify timer shutdown behavior.

Impact Analysis

If exploited, this could cause system instability or crashes in systems using batman-adv's tp_meter feature. It may lead to unexpected behavior in network performance monitoring or routing protocols relying on this component.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for CVE-2026-64093. If using batman-adv, ensure you are running a version with the timer_shutdown_sync() implementation. Reboot the system after applying the kernel update to activate the changes.

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