CVE-2026-63867 | In the Linux kernel, the following vulnerability has been re… | CVSS 8.2 HIGH

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: close TOCTOU race while computing rcv_wnd The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv wnd for the same packet. Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack.

Metadata

CVE ID: CVE-2026-63867
State: PUBLISHED
Assigner: Linux
Reserved: 2026-07-19 07:54 UTC
Published: 2026-07-19 14:18 UTC
Last updated: 2026-07-20 13:41 UTC
Vendor / Product: Linux / Linux
Sources: cve.org · NVD

Severity & Metrics

8.2 HIGH CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected products (2)

Vendor	Product	Platform	Versions
Linux	Linux	—	fa3fe2b150316b294f2c662653501273ff25bba8 < 301a33fd590c408a05c5df800e0cc1e6a8a2f8f8, fa3fe2b150316b294f2c662653501273ff25bba8 < 68364963e5baf03f16b4420292291f75c8f66497, fa3fe2b150316b294f2c662653501273ff25bba8 < 907ac6b1658e0277f979fcdfae2a753b495c1510, fa3fe2b150316b294f2c662653501273ff25bba8 < c4f4cf60797974873dbc8e100144682a6f2f861f …
Linux	Linux	—	5.11, 0 < 5.11, 5.15.210 ≤ 5.15., 6.1.176 ≤ 6.1. …

CVSS scores (1)

Score	Severity	Version	Source	Vector
8.2	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

References (7)