{"id":"CVE-2026-97566","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: kernel: drop pending ADD_ADDR when removing ID0\n\nThe in-kernel MPTCP path manager can leave a stale ADD_ADDR announcement\nentry alive when removing the id 0 …","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: kernel: drop pending ADD_ADDR when removing ID0\n\nThe in-kernel MPTCP path manager can leave a stale ADD_ADDR announcement\nentry alive when removing the id 0 …","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-617"],"vendor":"Linux","product":"Linux","affected":["Linux >= 740d798e8767d8a449902b1a1bbc70facfce19b5 < bacf23e7c9876c9f4170166b3597cb22ea3ed39b","Linux >= 740d798e8767d8a449902b1a1bbc70facfce19b5 < d4a67a880654e1bfe318a31bea0bdbb026a09ade","Linux >= 740d798e8767d8a449902b1a1bbc70facfce19b5 < 545616b4e7325be3c61fc082538cb06d14f7b1db","Linux >= 740d798e8767d8a449902b1a1bbc70facfce19b5 < 2ac7d6e620764f1fc79eb4edd3610a7a661981ca","Linux 5.13"],"published":"2026-09-25","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:18:04.090","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-97566","references":[{"url":"https://git.kernel.org/stable/c/2ac7d6e620764f1fc79eb4edd3610a7a661981ca","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/545616b4e7325be3c61fc082538cb06d14f7b1db","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bacf23e7c9876c9f4170166b3597cb22ea3ed39b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d4a67a880654e1bfe318a31bea0bdbb026a09ade","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97566.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-97566"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541203"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97566"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97566"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97566.mbox"},{"url":"https://git.kernel.org/stable/c/189d60057e5f3d6a62e3d71a3cc428c9150bc14f"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00206,"epssPercentile":0.10584,"cvssSource":"vendor","ingestedAt":"2026-09-25T11:06:38.914Z","slug":"CVE-2026-97566","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: kernel: drop pending ADD_ADDR when removing ID0\n\nThe in-kernel MPTCP path manager can leave a stale ADD_ADDR announcement\nentry alive when removing the id 0 endpoint. This happens because the id 0\nremoval path does not tear down pending announcements, unlike the non-zero\nid path.\n\nWhen the PM later reselects id 0 after adding another signal endpoint, it\nfinds the stale anno_list entry and hits WARN_ON_ONCE(mptcp_pm_is_kernel())\nin mptcp_pm_announced_alloc().\n\nRoot cause: asymmetry between removal paths.\n- Non-zero id path: mptcp_nl_remove_subflow_and_signal_addr() calls\n  mptcp_pm_remove_announced() to clean up.\n- Id 0 path: mptcp_nl_remove_id_zero_address() skips cleanup entirely.\n\nFix by making the id 0 path symmetric: call mptcp_pm_announced_remove()\nand decrement add_addr_signaled before queuing the RM_ADDR.\n\nSubtle detail: signal endpoints are stored in anno_list with port 0, but\nmsk_local carries the connection's local port. In other words, entries\nlinked to ID0 paths should have port == 0. A follow-up patch will ensure\nthat. mptcp_pm_announced_remove() uses use_port=true for comparison. So\nclear the port before the lookup.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10 · no fix planned: Red Hat Enterprise Linux 10 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97566.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":212333,"id":"CVE-2026-97566","ts":1790668150641,"field":"cvss","old":null,"new":"5.5"},{"seq":212332,"id":"CVE-2026-97566","ts":1790668150641,"field":"severity","old":"none","new":"medium"}]}