CVE-2026-72392
Received Received - Intake

NULL Pointer Dereference in Linux Kernel IPv6 FIB

Vulnerability report for CVE-2026-72392, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-15

Last updated on: 2026-08-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: fib6: fix NULL deref in fib6_walk_continue() on multi-batch dump inet6_dump_fib() saves its progress in cb->args[1] as a positional index within the current hash chain. Between batches, a concurrent fib6_new_table() can insert a new table at the chain head, shifting all existing entries. The saved index then lands on a different table, causing fib6_dump_table() to set w->root to the wrong table while w->node still points into the previous one. fib6_walk_continue() dereferences w->node->parent (NULL) and panics: BUG: kernel NULL pointer dereference, address: 0000000000000008 RIP: 0010:fib6_walk_continue+0x6e/0x170 Call Trace: <TASK> fib6_dump_table.isra.0+0xc5/0x240 inet6_dump_fib+0xf6/0x420 rtnl_dumpit+0x30/0xa0 netlink_dump+0x15b/0x460 netlink_recvmsg+0x1d6/0x2a0 ____sys_recvmsg+0x17a/0x190 Fix by storing tb->tb6_id in cb->args[1] instead of a positional index. On resume, skip entries until the id matches; a concurrent head-insert can never match the saved id, so the walker always resumes on the correct table.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-19
Generated
2026-09-04
AI Q&A
2026-08-15
EPSS Evaluated
2026-09-03
NVD
EUVD

Affected Vendors & Products

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

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a NULL pointer dereference flaw in the Linux kernel's IPv6 forwarding table (fib6) handling. It occurs during multi-batch dump operations when a concurrent operation shifts hash chain entries, causing the walker to reference an invalid memory location and trigger a kernel panic.

Detection Guidance

This vulnerability is specific to the Linux kernel's IPv6 forwarding table handling. Detection requires checking kernel logs for NULL pointer dereference errors in fib6_walk_continue or related IPv6 FIB (Forwarding Information Base) functions. Monitor system logs for kernel panics or crashes involving these functions.

Impact Analysis

This vulnerability can cause a system crash (kernel panic) when specific IPv6 routing table operations are performed concurrently. The crash may lead to denial of service, requiring a system reboot to restore normal operation.

Compliance Impact

This vulnerability causes a kernel panic due to a NULL pointer dereference in the IPv6 forwarding subsystem. It does not directly impact data confidentiality, integrity, or availability in a way that would violate GDPR or HIPAA requirements. However, system crashes could lead to service disruptions affecting compliance with uptime or reliability standards.

Mitigation Strategies

Apply the latest kernel security patches from your Linux distribution. If a patch is not yet available, consider disabling IPv6 forwarding temporarily if not required, or restrict IPv6 traffic through firewall rules until the fix is applied.

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