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CVE-2026-23364: ksmbd: Compare MACs in constant time

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-25 · updated 2026-10-15

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().

Affected products

• Linux kernel: from 5.15.1 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.19; from 6.19 before 6.19.7; 5.15, 7.0-rc1, 7.0-rc2, 7.0-rc3, 7.0-rc4, 7.0-rc5 (+2) — fixed in 6.1.167, 6.12.78, 6.18.19, 6.19.7, 6.6.130

How to fix

Upgrade to a fixed version: Linux kernel 6.1.167, 6.12.78, 6.18.19, 6.19.7. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/2cdc56ed67615ba0921383a688f24415ebe065f3
• https://git.kernel.org/stable/c/307afccb751f542246bd5dc68a2c1ffe1a78418c
• https://git.kernel.org/stable/c/8a665d733940592e671ec6afadcd0be80a091a80
• https://git.kernel.org/stable/c/93c0a22fec914ec4b697e464895a0f594e29fb28
• https://git.kernel.org/stable/c/c5794709bc9105935dbedef8b9cf9c06f2b559fa
• https://git.kernel.org/stable/c/cd52a0e309659537048a864211abc3ea4c5caa63
• https://git.kernel.org/stable/c/f4588b85efd6007d46b80aa1b9fb746628ffb3dc
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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