CVE-2025-40279

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BaseFortify

Publication date: 2025-12-06

Last updated on: 2025-12-08

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: net: sched: act_connmark: initialize struct tc_ife to fix kernel leak In tcf_connmark_dump(), the variable 'opt' was partially initialized using a designatied initializer. While the padding bytes are reamined uninitialized. nla_put() copies the entire structure into a netlink message, these uninitialized bytes leaked to userspace. Initialize the structure with memset before assigning its fields to ensure all members and padding are cleared prior to beign copied.

CVSS Scores

EPSS Scores

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Meta Information

Published

2025-12-06

Last Modified

2025-12-08

Generated

2026-07-06

AI Q&A

2025-12-07

EPSS Evaluated

2026-07-05

NVD

CVE-2025-40279

EUVD

EUVD-2025-201576

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves the act_connmark module where a structure (tc_ife) was only partially initialized. Because some padding bytes remained uninitialized, when the structure was copied into a netlink message, these uninitialized bytes leaked kernel memory contents to userspace. The fix was to fully initialize the structure with memset before setting its fields to prevent leaking uninitialized data.

Impact Analysis

This vulnerability can lead to unintended leakage of kernel memory contents to userspace, potentially exposing sensitive information or internal kernel data that should remain protected. This could be exploited by an attacker to gain insights into the kernel memory layout or sensitive data, which might aid further attacks.

Mitigation Strategies

Apply the patch or update to the fixed Linux kernel version that initializes the struct tc_ife properly to prevent kernel memory leaks. Until then, avoid exposing vulnerable kernel interfaces to untrusted userspace processes.

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