CVE-2026-74582
Received Received - Intake

Buffer Overflow in Linux Kernel Packet Handling

Publication date: 2026-08-21

Last updated on: 2026-08-21

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: packet: use consistent hard_header_len in non-ring send paths packet_snd() reads dev->hard_header_len multiple times while allocating and constructing an skb. Device reconfiguration can change this value concurrently, for example through bonding device type changes. For SOCK_RAW, packet_snd() can save a larger value in reserve and later allocate headroom using a smaller value. Moving skb->data back by reserve then places it before skb->head, and the following copy from userspace can attempt an out-of-bounds write. packet_sendmsg_spkt() has the same issue because it calculates its reservation and header offset from separate reads before dropping the RCU read lock to allocate the skb. Add LL_RESERVED_SPACE_EX() for callers that already saved a header length. Read hard_header_len once in packet_snd() and use it for allocation and construction. In packet_sendmsg_spkt(), preserve the allocation-time value through the device lookup retry. 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
2026-08-21
Last Modified
2026-08-21
Generated
2026-08-21
AI Q&A
2026-08-21
EPSS Evaluated
N/A
NVD
CVE-2026-74582
EUVD
EUVD-2026-64004

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 vulnerability in the Linux kernel involves a race condition in the packet_snd() function where dev->hard_header_len is read multiple times. If the device is reconfigured concurrently, such as through bonding changes, the value may change between reads. For SOCK_RAW sockets, this can lead to an out-of-bounds write when userspace data is copied into the allocated skb headroom.

Impact Analysis

This vulnerability could allow an attacker to execute arbitrary code or cause a denial of service by triggering an out-of-bounds memory write. It primarily affects systems using raw packet sockets, which are often used for network monitoring or custom networking applications.

Mitigation Strategies

Apply the latest Linux kernel security patches to address the packet_snd() and packet_sendmsg_spkt() vulnerabilities. Monitor for unusual network activity or crashes that may indicate exploitation.

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