CVE-2026-99999
Received Received - Intake

IPv4 Checksum Validation Bypass in Linux Kernel

Publication date: 2026-10-15

Last updated on: 2026-10-15

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ipv4: validate checksum_start before completing checksum If a packet with bad checksum metadata gets into the ipv4 stack, skb_checksum_help can corrupt the network header and cause a bunch of mischief. This was discovered and reported by Paulos, and has been reporoduced by others independently since. We really shouldn't allow such packets in, but as a defence in depth measure, let's also check before we complete the checksum. A more complete validation at input is forthcoming, but needs more work.

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Meta Information

Published
2026-10-15
Last Modified
2026-10-15
Generated
2026-10-15
AI Q&A
2026-10-15
EPSS Evaluated
N/A
NVD
CVE-2026-99999
EUVD
EUVD-2026-102044

Affected Vendors & Products

Showing 9 associated CPEs
Vendor Product Version / Range
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux f43798c27684ab925adde7d8acc34c78c6e50df8
Linux Linux 2.6.27

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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 improper validation of checksum metadata in IPv4 packets. When a packet with bad checksum metadata enters the IPv4 stack, the system's checksum handling function (skb_checksum_help) can corrupt the network header, leading to potential system instability or unauthorized access.

Detection Guidance

This vulnerability is specific to the Linux kernel's IPv4 networking stack and requires kernel-level inspection. There are no direct user-space commands to detect it, but monitoring for unusual network behavior or crashes may indicate exploitation. Kernel logs or security tools analyzing network packet handling could help identify anomalies.

Impact Analysis

This flaw could allow attackers to leak host memory over the network, crash the host machine, or execute code on the host with full administrator privileges. It compromises system integrity and confidentiality by enabling unauthorized access and control.

Compliance Impact

This vulnerability could potentially lead to unauthorized memory access or code execution on affected systems, which may violate data protection requirements under GDPR (e.g., unauthorized data access) and HIPAA (e.g., unauthorized access to protected health information). The high-severity nature of the flaw (CVSS 9.3) suggests significant risk to confidentiality and integrity of data, requiring immediate patching to maintain compliance.

Mitigation Strategies

Apply the latest Linux kernel security patches immediately. Update your system to a version that includes the fix for this vulnerability. If patches are not yet available, consider isolating vulnerable systems or restricting network access until updates are applied.

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