CVE-2026-74668

Received Received - Intake

Packet Header Length Mismatch in Linux Kernel

Publication date: 2026-08-22

Last updated on: 2026-08-27

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: packet: use consistent hard_header_len in TX_RING send path tpacket_snd() reads dev->hard_header_len independently for skb allocation and header construction in tpacket_fill_skb(). Concurrent netdevice reconfiguration can therefore make the reserved headroom smaller than the amount later pushed, or make copylen - hard_header_len negative. Snapshot hard_header_len once before processing ring frames and use it for the frame limit, headroom allocation, copy length, and skb construction. Pass the snapshot to tpacket_fill_skb(). The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-22

Last Modified

2026-08-27

Generated

2026-09-12

AI Q&A

2026-08-22

EPSS Evaluated

2026-09-10

NVD

CVE-2026-74668

EUVD

EUVD-2026-64355

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a race condition in the packet socket implementation. The issue occurs when tpacket_snd() reads dev->hard_header_len separately for skb allocation and header construction. If the network device is reconfigured concurrently, the reserved headroom may become insufficient, leading to potential buffer overflows or negative copy lengths during packet transmission.

Detection Guidance

This vulnerability is specific to the Linux kernel's packet socket implementation and requires kernel-level detection. There are no direct user-space commands to detect it. Monitoring for kernel crashes, packet transmission failures, or unusual network behavior during high-load scenarios may indicate issues. Check kernel logs for errors related to packet sockets or network device reconfiguration.

Impact Analysis

An attacker could exploit this to cause denial-of-service conditions, crash the system, or potentially execute arbitrary code with kernel privileges. Systems using packet sockets for high-speed networking or monitoring may be particularly affected.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a Linux kernel networking issue that could lead to packet handling errors but does not involve data breaches, unauthorized access, or privacy violations typically addressed by these regulations.

Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve the tpacket_snd() vulnerability. Monitor network device configurations for inconsistencies in hard_header_len during runtime.

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