CVE-2026-97568

mptcp: syncookies: remember the request backup flag

Published Sep 25, 2026 CVSS n/a EPSS < 1% KEV · Not listed

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

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`1008f2bcbc8e461c1df3aebba30ac4f616ebe570`	affected	< c97fa2c7ada82d4cac1c6c00643238dc4c462f15
`6f01f41b6a492ddf2da7609967cfaf57e7ca48a7`	affected	< 1668b34452009d27be3262646de748a3e48ffd51
`09176f80995105c62939728fbad5c437d61e7ff4`	affected	< b138e7dc719f0a3949de8bb6500b8cf1604eea06
`8ed3e34c766e8264d5d2e0436f86c51604d6a8a7`	affected	< 360d99258a6402cb8e49771460944f19f04d25b7
`efd340bf3d7779a3a8ec954d8ec0fb8a10f24982`	affected	< 61178d0b85b4b1b53e78b06e89d018d22d102f88
`efd340bf3d7779a3a8ec954d8ec0fb8a10f24982`	affected	< 00b2bd518911e0daab00f4749cce68c191ccebb4
`efd340bf3d7779a3a8ec954d8ec0fb8a10f24982`	affected	< 06d649f9cd03a9f8e768a658b20acf8d2c8022e0
`efd340bf3d7779a3a8ec954d8ec0fb8a10f24982`	affected	< b76c0e28b392620dfbaf92cdeedbf115820b44cb
`73e2baa301ee3f62ff971e68877adeb37f98cc67`	affected	—
`5.10.224`	affected	< 5.10.271
`5.15.165`	affected	< 5.15.222
`6.1.104`	affected	< 6.1.189
`6.6.45`	affected	< 6.6.158
`6.10.4`	affected	< 6.11

Linux

affected

Version	Status	Constraints
`6.11`	affected	—
`0`	unaffected	< 6.11
`5.10.271`	unaffected	≤ 5.10.*
`5.15.222`	unaffected	≤ 5.15.*
`6.1.189`	unaffected	≤ 6.1.*
`6.6.158`	unaffected	≤ 6.6.*
`6.12.111`	unaffected	≤ 6.12.*
`6.18.53`	unaffected	≤ 6.18.*
`7.2.7`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[efd340bf3d7779a3a8ec954d8ec0fb8a10f24982,61178d0b85b4b1b53e78b06e89d018d22d102f88)`	affected	code_commit	—
`[efd340bf3d7779a3a8ec954d8ec0fb8a10f24982,00b2bd518911e0daab00f4749cce68c191ccebb4)`	affected	code_commit	—
`[efd340bf3d7779a3a8ec954d8ec0fb8a10f24982,06d649f9cd03a9f8e768a658b20acf8d2c8022e0)`	affected	code_commit	—
`[efd340bf3d7779a3a8ec954d8ec0fb8a10f24982,b76c0e28b392620dfbaf92cdeedbf115820b44cb)`	affected	code_commit	—
`1008f2bcbc8e461c1df3aebba30ac4f616ebe570`	affected	code_commit	—
`6f01f41b6a492ddf2da7609967cfaf57e7ca48a7`	affected	code_commit	—
`09176f80995105c62939728fbad5c437d61e7ff4`	affected	code_commit	—
`8ed3e34c766e8264d5d2e0436f86c51604d6a8a7`	affected	code_commit	—
`73e2baa301ee3f62ff971e68877adeb37f98cc67`	affected	code_commit	—
`[5.10.224,5.11)`	affected	semver	—
`[5.15.165,5.16)`	affected	semver	—
`[6.1.104,6.2)`	affected	semver	—
`[6.6.45,6.7)`	affected	semver	—
`[6.10.4,6.11)`	affected	semver	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`6.11`	affected	semver	—
`[0,6.11)`	unaffected	semver	—
`[0,6.13.0)`	unaffected	semver	—
`[0,6.19.0)`	unaffected	semver	—
`[0,7.3.0)`	unaffected	semver	—
`[0,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4817-1	linux-6.12 security update
Debian DLA	DLA-4841-1	linux security update
Debian DSA	DSA-6528-1	linux security update
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9022-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9023-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9029-1	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-9039-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-9091-1	Linux kernel (NVIDIA Tegra) vulnerabilities

Metrics

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.216% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
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

History

Oct 3, 2026 11:15 AM Added references View changes

Type	Values Removed	Values Added
References		https://git.kernel.org/stable/c/1668b34452009d27be3262646de748a3e48ffd51 https://git.kernel.org/stable/c/360d99258a6402cb8e49771460944f19f04d25b7 https://git.kernel.org/stable/c/b138e7dc719f0a3949de8bb6500b8cf1604eea06 https://git.kernel.org/stable/c/c97fa2c7ada82d4cac1c6c00643238dc4c462f15

Sep 25, 2026 11:00 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-788

Sep 25, 2026 10:30 AM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
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.
Title		mptcp: syncookies: remember the request backup flag
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/00b2bd518911e0daab00f4749cce68c191ccebb4 https://git.kernel.org/stable/c/06d649f9cd03a9f8e768a658b20acf8d2c8022e0 https://git.kernel.org/stable/c/61178d0b85b4b1b53e78b06e89d018d22d102f88 https://git.kernel.org/stable/c/b76c0e28b392620dfbaf92cdeedbf115820b44cb