What’s Vulnerable › Vulnerabilities

CVE-2026-97568: mptcp: syncookies: remember the request backup flag

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-25 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: syncookies: remember the request backup flag Instead of using an uninitialised bit when copying the info in subflow_ulp_clone(). To fix this, no need to extend the join_entry structure: backup is coming from struct mptcp_subflow_request_sock, only one bit. Do the same here by using one bit for both.

Affected products

• Linux kernel: from 5.10.224 before 5.10.271; from 5.15.165 before 5.15.222; from 6.1.104 before 6.1.189; from 6.6.45 before 6.6.158; from 6.10.4 before 6.11; 6.11 — fixed in 5.10.271, 5.15.222, 6.1.189, 6.11, 6.6.158, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 5.10.271, 5.15.222, 6.1.189, 6.11. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/00b2bd518911e0daab00f4749cce68c191ccebb4
• https://git.kernel.org/stable/c/06d649f9cd03a9f8e768a658b20acf8d2c8022e0
• https://git.kernel.org/stable/c/1668b34452009d27be3262646de748a3e48ffd51
• https://git.kernel.org/stable/c/360d99258a6402cb8e49771460944f19f04d25b7
• https://git.kernel.org/stable/c/61178d0b85b4b1b53e78b06e89d018d22d102f88
• https://git.kernel.org/stable/c/b138e7dc719f0a3949de8bb6500b8cf1604eea06
• https://git.kernel.org/stable/c/b76c0e28b392620dfbaf92cdeedbf115820b44cb
• https://git.kernel.org/stable/c/c97fa2c7ada82d4cac1c6c00643238dc4c462f15

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