CVE-2026-63867
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.
SeverityHigh
CVSS8.2
Exploit probability—
Product
Linux Kernel
PublishedJul 19, 2026
First seenJul 19, 2026
Weakness typeCWE-362Race condition
How to fix
Update
- linux linux_kernel5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| linux linux_kernel | 5.11 ≤ v < 5.15.210, 5.16 ≤ v < 6.1.176, 6.2 ≤ v < 6.6.143, 6.7 ≤ v < 6.12.94, 6.13 ≤ v < 6.18.36, 6.19 ≤ v < 7.0.13, 7.1 | 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13 |
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