{"id":"CVE-2026-99155","title":"scsi: xen/scsifront: Check for a NULL shadow entry on a backend response","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: xen/scsifront: Check for a NULL shadow entry on a backend response\n\nscsifront_do_response() validates the rqid in a backend response against\nVSCSIIF_MAX_REQS befo…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 < 1d91ec793d6c80eca963d426e0da832d40a062df","Linux >= 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 < 15791e57f57f7050014d08cfe239d4aa1e6b94b0","Linux >= 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 < 8c8222c255772713eb36cde695777a1fce224917","Linux 5.19"],"published":"2026-10-28","updated":"2026-10-28","sourceUpdated":"2026-10-28T10:35:09.733Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99155","references":[{"url":"https://git.kernel.org/stable/c/1d91ec793d6c80eca963d426e0da832d40a062df"},{"url":"https://git.kernel.org/stable/c/15791e57f57f7050014d08cfe239d4aa1e6b94b0"},{"url":"https://git.kernel.org/stable/c/8c8222c255772713eb36cde695777a1fce224917"}],"tags":["cve.org"],"ingestedAt":"2026-10-28T11:09:40.402Z","slug":"CVE-2026-99155","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nscsi: xen/scsifront: Check for a NULL shadow entry on a backend response\n\nscsifront_do_response() validates the rqid in a backend response against\nVSCSIIF_MAX_REQS before using it to index info->shadow[], but then\ndereferences the entry to test ->inflight without checking that the slot\nis populated.  Shadow slots are NULL before a command is submitted (the\nhost private area is zeroed at allocation) and are reset to NULL in\n_scsifront_put_rqid() once a request completes, so an in-range rqid that\ndoes not correspond to an outstanding request makes the frontend\ndereference a NULL pointer.\n\nA malicious or buggy backend can thus crash the guest by returning a\nresponse whose rqid is in range but not in flight -- for example a\nspurious response before any command has been issued, or a duplicate of\none already completed.  The ring has only VSCSIIF_MAX_REQS (16) slots,\nso before the first command every in-range rqid selects a NULL slot.\n\nReject a response whose shadow slot is not populated.\n\n## Affected\n\n- `Linux >= 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 < 1d91ec793d6c80eca963d426e0da832d40a062df`\n- `Linux >= 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 < 15791e57f57f7050014d08cfe239d4aa1e6b94b0`\n- `Linux >= 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 < 8c8222c255772713eb36cde695777a1fce224917`\n- `Linux 5.19`\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":[]}