High 8.2Published Jul 19, 2026

CVE-2026-63867mptcp: close TOCTOU race while computing rcv_wnd

Updated under an hour ago (Oct 28, 2026, 4:40 AM ET)

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Exploited in the last 30 days

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.

CVSS: 8.2 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness (CWE): CWE-362
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from fa3fe2b150316b294f2c662653501273ff25bba8 before 301a33fd590c408a05c5df800e0cc1e6a8a2f8f8; from fa3fe2b150316b294f2c662653501273ff25bba8 before 68364963e5baf03f16b4420292291f75c8f66497; from fa3fe2b150316b294f2c662653501273ff25bba8 before 907ac6b1658e0277f979fcdfae2a753b495c1510; from fa3fe2b150316b294f2c662653501273ff25bba8 before c4f4cf60797974873dbc8e100144682a6f2f861f; from fa3fe2b150316b294f2c662653501273ff25bba8 before 3b8cbba7c0ed31189c89f90be247b8973ffa79ef; from fa3fe2b150316b294f2c662653501273ff25bba8 before 8f4f0a157e8436a05bf8c3670b24dbc258911c43; from fa3fe2b150316b294f2c662653501273ff25bba8 before 8ab24fdebc369c0dfb90f82c1650b1e66662bb45	CNA record
linux linux_kernel linux:linux_kernel	from 5.11 before 5.15.210; from 5.16 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; from 6.19 before 7.0.13; 7.1; 7.1; and 4 more ranges	NVD

References

References

https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8	patch
https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497	patch
https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510	patch
https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f	patch
https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef	patch
https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43	patch
https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.