{"id":"CVE-2026-45889","summary":"mptcp: do not account for OoO in mptcp_rcvbuf_grow()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: do not account for OoO in mptcp_rcvbuf_grow()\n\nMPTCP-level OoOs are physiological when multiple subflows are active\nconcurrently and will not cause retransmissions nor are caused by\ndrops.\n\nAccounting for them in mptcp_rcvbuf_grow() causes the rcvbuf slowly\ndrifting towards tcp_rmem[2].\n\nRemove such accounting. Note that subflows will still account for TCP-level\nOoO when the MPTCP-level rcvbuf is propagated.\n\nThis also closes a subtle and very unlikely race condition with rcvspace\ninit; active sockets with user-space holding the msk-level socket lock,\ncould complete such initialization in the receive callback, after that the\nfirst OoO data reaches the rcvbuf and potentially triggering a divide by\nzero Oops.","modified":"2026-07-15T01:48:50.270386759Z","published":"2026-05-27T12:17:00.509Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45889.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/400ee4854adef1e4983812a3decf6717ea020136"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6b329393502e5857662b851a13f947209c588587"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fb7bf00b04a6b48859f52035d4e745848c2b4c79"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45889.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45889"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e118cdc34dd109562b64f6a397f68cd33b041d5b"},{"fixed":"fb7bf00b04a6b48859f52035d4e745848c2b4c79"},{"fixed":"400ee4854adef1e4983812a3decf6717ea020136"},{"fixed":"6b329393502e5857662b851a13f947209c588587"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-45889.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.18.0"},{"fixed":"6.18.14"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-45889.json"}}],"schema_version":"1.7.5"}