CVE-2026-74668
Received Received - Intake

Packet Header Length Mismatch in Linux Kernel

Publication date: 2026-08-22

Last updated on: 2026-08-22

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.

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
CVE-2026-74668
EUVD
EUVD-2026-64355

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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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.

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.

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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