CVE-2026-64576
Received Received - Intake

Kernel panic due to uninitialized extack in Linux kernel

Publication date: 2026-08-05

Last updated on: 2026-08-05

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: nexthop: initialize extack in nh_res_bucket_migrate() nh_res_bucket_migrate() passes an uninitialized netlink_ext_ack to call_nexthop_res_bucket_notifiers(). When nh_notifier_res_bucket_info_init() fails (e.g. the kzalloc returns -ENOMEM), the error is propagated back before any notifier sets extack._msg, and the error path formats the stale pointer with pr_err_ratelimited("%s\n", extack._msg). With CONFIG_INIT_STACK_NONE this dereferences uninitialized stack memory: Oops: general protection fault, probably for non-canonical address ... KASAN: maybe wild-memory-access in range [...] RIP: 0010:string (lib/vsprintf.c:730) vsnprintf (lib/vsprintf.c:2945) _printk (kernel/printk/printk.c:2504) nh_res_bucket_migrate (net/ipv4/nexthop.c:1816) nh_res_table_upkeep (net/ipv4/nexthop.c:1866) rtm_new_nexthop (net/ipv4/nexthop.c:3323) rtnetlink_rcv_msg (net/core/rtnetlink.c:7076) netlink_sendmsg (net/netlink/af_netlink.c:1900) Kernel panic - not syncing: Fatal exception Zero-initialize extack so _msg is NULL on error paths that never set it.

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Meta Information

Published
2026-08-05
Last Modified
2026-08-05
Generated
2026-08-05
AI Q&A
2026-08-05
EPSS Evaluated
N/A
NVD
CVE-2026-64576
EUVD
EUVD-2026-53270

Affected Vendors & Products

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

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where an uninitialized memory issue occurs in the nexthop functionality. The function nh_res_bucket_migrate() passes an uninitialized netlink_ext_ack structure to another function. If an error occurs during memory allocation, the error path may dereference uninitialized stack memory, leading to a kernel panic or general protection fault.

Detection Guidance

This vulnerability is specific to the Linux kernel and may not have direct detection commands. Monitor kernel logs for general protection faults or KASAN warnings related to nexthop operations. Check for crashes in netlink or rtnetlink subsystems during nexthop operations.

Impact Analysis

This vulnerability can cause system crashes, kernel panics, or unexpected behavior due to memory corruption. Attackers could exploit it to trigger denial-of-service conditions, potentially disrupting network services or causing system instability.

Compliance Impact

This vulnerability is a kernel-level issue in the Linux operating system that could lead to a kernel panic or memory corruption. It does not directly relate to data privacy or security controls typically addressed by GDPR or HIPAA. Compliance with these standards would depend on the specific implementation and environment where the Linux kernel is used.

Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. If patching is not immediately possible, consider disabling CONFIG_INIT_STACK_NONE to avoid uninitialized stack memory issues. Monitor system logs for related errors.

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