CVE-2026-63867
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.27%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 8.2 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- EPSS
- 0.27% probability · 20th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-367, CWE-362
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
EPSS 0.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8Patch
- https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79efPatch
- https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497Patch
- https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45Patch
- https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43Patch
- https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510Patch
- https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861fPatch
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.