Junglewise Threat Intelligence

CVE-2026-43451: Linux kernel memory leak in Netfilter nfnetlink_queue

CVE-2026-43451 · Severity: medium · CVSS 5.5 · Published 2026-05-08

Technologies: Linux Kernel. Vendors: Linux.

Executive brief

A memory leak vulnerability exists in the Linux kernel's networking subsystem, specifically within the Netfilter component used for firewalling and packet filtering. An attacker could exploit this flaw to repeatedly trigger a specific error condition during network bridge processing, causing the system to consume and never release memory. Over time, this leads to kernel memory exhaustion, resulting in a system crash or a denial-of-service condition that disrupts operations.

Technical details

A memory leak (CWE-401) exists in net/netfilter/nfnetlink_queue.c within the nfqnl_recv_verdict() function. When processing PF_BRIDGE packets, the function calls find_dequeue_entry() to take ownership of a queue entry, but fails to free the nf_queue_entry, its associated sk_buff, or release net_device/net refcounts if nfqa_parse_bridge() returns an error. This error path occurs when specific VLAN attributes (like NFQA_VLAN_TCI) are missing despite the presence of NFQA_VLAN. A local attacker can exploit this to exhaust kernel memory and cause a denial-of-service. The issue has been patched by ensuring nfqnl_reinject() is called with an NF_DROP verdict on the error path to properly release resources.

Affected products

  • Linux Linux kernel 4.7 to 5.10.253, 5.11 to 5.15.203, 5.16 to 6.1.167, 6.2 to 6.6.130, 6.7 to 6.12.78, 6.13 to 6.18.19, 6.19 to 6.19.9

Timeline

  • 2026-03-08: other: Vulnerability fixed in upstream commits
  • 2026-05-08: disclosed
  • 2026-05-08: advisory

References

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