CVE-2026-98031
Received Received - Intake

nexthop: extack initialization failure in remove_nh_grp_entry()

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: nexthop: Initialize extack in remove_nh_grp_entry() remove_nh_grp_entry() prints the extack message when a listener fails to replace the reduced nexthop group. However, extack is not initialized and listeners are not required to set a message when returning an error. Neither netdevsim nor mlxsw do so when an allocation fails, resulting in the dereference of an uninitialized stack pointer. Fix by zero-initializing extack, as was done in commit 6347c5314cee ("nexthop: initialize extack in nh_res_bucket_migrate()").

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Meta Information

Published
2026-09-25
Last Modified
2026-09-25
Generated
2026-09-25
AI Q&A
2026-09-25
EPSS Evaluated
N/A
NVD
CVE-2026-98031
EUVD
EUVD-2026-86684

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 remove_nh_grp_entry() function may dereference an uninitialized stack pointer when printing extack error messages. The extack variable is not initialized before use, which can lead to undefined behavior if a listener fails to replace a reduced nexthop group.

Detection Guidance

This vulnerability involves an uninitialized stack pointer in the Linux kernel's nexthop group handling. Detection requires checking kernel logs for crashes or errors related to nexthop operations, particularly during nexthop group removal or migration. Monitor for kernel oops or warnings about extack dereferencing.

Impact Analysis

This vulnerability could cause system instability or crashes in Linux systems using nexthop groups. It may lead to kernel panics or unexpected behavior if the uninitialized extack is accessed during error handling in networking operations.

Mitigation Strategies

Apply the kernel patch that initializes extack in remove_nh_grp_entry(), as referenced in commit 6347c5314cee. Update to a kernel version containing this fix. If immediate patching is not possible, restrict access to nexthop group operations until patched.

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