CVE-2026-98027
Received Received - Intake

Buffer Overflow in Linux Kernel Networking

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size mv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while dumping the policy IDR, clobbering the input value before it has been looked at. That input is the number of entries the caller had room for. ETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the buffer from the rule_cnt userspace passes in, so once an admin has installed policy rules any user can ask for fewer slots than there are rules and run off the end of the allocation. A rule_cnt of 0 leaves the buffer pointer NULL and the walk dereferences it. Count into a local so the caller's limit survives the walk, and stop with -EMSGSIZE once it is reached.

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Meta Information

Published
2026-09-25
Last Modified
2026-09-25
Generated
2026-09-25
AI Q&A
2026-09-25
EPSS Evaluated
N/A
NVD
CVE-2026-98027
EUVD
EUVD-2026-86680

Affected Vendors & Products

Currently, no data is known.

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Exploitability

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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 buffer overflow in the mv88e6xxx network driver. The function mv88e6xxx_get_rxnfc() incorrectly uses the caller's buffer size as a write index while dumping policy rules, potentially overwriting memory and causing crashes or privilege escalation.

Detection Guidance

This vulnerability can be detected by checking for unauthorized access attempts or crashes in systems using the mv88e6xxx network driver. Monitor logs for ETHTOOL_GRXCLSRLALL ioctl calls with unusual rule_cnt values. No specific commands are provided in the context.

Impact Analysis

An attacker could exploit this to crash the system or gain elevated privileges. Since no CAP_NET_ADMIN is required, any user can trigger the flaw by requesting fewer rules than exist, leading to memory corruption.

Mitigation Strategies

Update the Linux kernel to a patched version that resolves this issue. Restrict access to ETHTOOL_GRXCLSRLALL ioctl calls if possible. Monitor for policy rule misuse until patched.

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