CVE-2026-23364
Received Received - Intake
Timing Attack Vulnerability in Linux ksmbd MAC Comparison

Publication date: 2026-03-25

Last updated on: 2026-04-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: Compare MACs in constant time To prevent timing attacks, MAC comparisons need to be constant-time. Replace the memcmp() with the correct function, crypto_memneq().
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Meta Information
Published
2026-03-25
Last Modified
2026-04-24
Generated
2026-06-16
AI Q&A
2026-03-25
EPSS Evaluated
2026-06-15
NVD
CVE-2026-23364
EUVD
EUVD-2026-15344
Affected Vendors & Products
Showing 13 associated CPEs
Vendor Product Version / Range
linux linux_kernel 5.15
linux linux_kernel From 6.19 (inc) to 6.19.7 (exc)
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel From 6.2 (inc) to 6.6.130 (exc)
linux linux_kernel From 5.15.1 (inc) to 6.1.167 (exc)
linux linux_kernel From 6.13 (inc) to 6.18.19 (exc)
linux linux_kernel From 6.7 (inc) to 6.12.78 (exc)
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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 the ksmbd component where Message Authentication Codes (MACs) were compared using a standard memory comparison function (memcmp()). This approach is vulnerable to timing attacks because the time taken to compare MACs can vary depending on the data, potentially leaking information.

The fix replaces memcmp() with crypto_memneq(), a function designed to perform MAC comparisons in constant time, preventing attackers from gaining information through timing analysis.

Impact Analysis

This vulnerability can allow attackers to perform timing attacks to infer the correct MAC values by measuring the time taken to compare MACs. This could lead to unauthorized access or data tampering if an attacker successfully forges valid MACs.

By exploiting this, attackers might bypass authentication or integrity checks, potentially compromising system security.

Mitigation Strategies

The vulnerability is resolved by updating the Linux kernel to a version where the ksmbd component uses constant-time MAC comparison by replacing memcmp() with crypto_memneq().

Therefore, the immediate mitigation step is to update your Linux kernel to the fixed version that includes this patch.

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