{"cve":"CVE-2026-63867","nvd":{"published":"2026-07-19T15:16:53.617","modified":"2026-10-19T21:17:08.160","status":"Undergoing Analysis","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: close TOCTOU race while computing rcv_wnd\n\nThe MPTCP output path access locklessly the MPTCP-level ack_seq\nin multiple times, using possibly different values for the data_ack\nin the DSS option and to compute the announced rcv wnd for the same\npacket.\n\nRefactor the cote to avoid inconsistencies which may confuse the\npeer. Also ensure that the MPTCP level rcv wnd is updated only when\nthe egress packet actually contains a DSS ack.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","score":8.2},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8","https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef","https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497","https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45","https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43"],"products":[],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2026-63867","score":0.00274,"percentile":0.19584,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}