{"id":"CVE-2026-98773","title":"USB: cdc-acm: skip URB restart in port_shutdown if disconnected","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: cdc-acm: skip URB restart in port_shutdown if disconnected\n\nacm_port_shutdown() is called from the tty-port machinery whenever the\nlast user closes the port.  acm_…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 603d5a7110832e10165d21f9a1486399457177de < 9742905d9ed5bf23ebe4c100dec80b6bc50fb522","Linux >= 5d29d7ff8679e5a525f22da467ba33c042e8029b < a0ed07b5bbb2d8fcef86810453216070691816e7","Linux >= f58752ebcb35e156c85cd1a82d6579c7af3b9023 < 420ca35af891d33522cc08504768ccd60a4c450a","Linux >= f58752ebcb35e156c85cd1a82d6579c7af3b9023 < dc614d6bc991740d41d5a99ac7765c4b675dda88","Linux d826061aa64cb28089bf4c73e301dd7928662b84","Linux 8fb82e3555a7d56a05d8ef0edee9859f889c0860","Linux 283f8162cc3c82086537cbc7dc01870dbeb07a91","Linux f77f10bc76c2da86b4248269472f6d971e37828b","Linux >= 6.12.83 < 6.12.113","Linux >= 6.18.24 < 6.18.56","Linux >= 6.1.175 < 6.2","Linux >= 6.6.136 < 6.7","Linux >= 6.19.14 < 6.20","Linux >= 7.0.1 < 7.1","Linux 7.1"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:48:09.093Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98773","references":[{"url":"https://git.kernel.org/stable/c/9742905d9ed5bf23ebe4c100dec80b6bc50fb522"},{"url":"https://git.kernel.org/stable/c/a0ed07b5bbb2d8fcef86810453216070691816e7"},{"url":"https://git.kernel.org/stable/c/420ca35af891d33522cc08504768ccd60a4c450a"},{"url":"https://git.kernel.org/stable/c/dc614d6bc991740d41d5a99ac7765c4b675dda88"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T16:47:32.491Z","slug":"CVE-2026-98773","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nUSB: cdc-acm: skip URB restart in port_shutdown if disconnected\n\nacm_port_shutdown() is called from the tty-port machinery whenever the\nlast user closes the port.  acm_disconnect() sets acm->disconnected and\ncalls tty_port_tty_vhangup(), which eventually triggers port_shutdown().\nAt that point acm_disconnect() has already called acm_poison_urbs() and\nis about to free the control and read URBs.\n\nHowever, acm_port_shutdown() unconditionally calls acm_unpoison_urbs()\nand, when the ALWAYS_POLL_CTRL quirk is set, immediately re-submits the\nctrlurb and all read URBs.  If the concurrent acm_disconnect() then\nfrees those URBs and their DMA buffers while they are in-flight, the\nresult is a use-after-free in acm_ctrl_irq() or acm_read_bulk_callback()\naccessing the freed DMA memory.\n\nFix by checking acm->disconnected after draining the delayed anchor and\nreturning early: if we are in a disconnect path the URBs must remain\npoisoned and must not be resubmitted.\n\nThe early return is placed after the delayed-anchor drain loop because\nthat loop only cancels write-side accounting (wb->use = false and\nautopm counter) and does not touch the hardware path.\n\n## Affected\n\n- `Linux >= 603d5a7110832e10165d21f9a1486399457177de < 9742905d9ed5bf23ebe4c100dec80b6bc50fb522`\n- `Linux >= 5d29d7ff8679e5a525f22da467ba33c042e8029b < a0ed07b5bbb2d8fcef86810453216070691816e7`\n- `Linux >= f58752ebcb35e156c85cd1a82d6579c7af3b9023 < 420ca35af891d33522cc08504768ccd60a4c450a`\n- `Linux >= f58752ebcb35e156c85cd1a82d6579c7af3b9023 < dc614d6bc991740d41d5a99ac7765c4b675dda88`\n- `Linux d826061aa64cb28089bf4c73e301dd7928662b84`\n- `Linux 8fb82e3555a7d56a05d8ef0edee9859f889c0860`\n- `Linux 283f8162cc3c82086537cbc7dc01870dbeb07a91`\n- `Linux f77f10bc76c2da86b4248269472f6d971e37828b`\n- `Linux >= 6.12.83 < 6.12.113`\n- `Linux >= 6.18.24 < 6.18.56`\n- `Linux >= 6.1.175 < 6.2`\n- `Linux >= 6.6.136 < 6.7`\n- `Linux >= 6.19.14 < 6.20`\n- `Linux >= 7.0.1 < 7.1`\n- `Linux 7.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}