{"id":"AZL-104430","summary":"CVE-2026-97926 affecting package kernel 6.6.157.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nufs: validate cylinder group metadata before caching it\n\nufs_read_cylinder() copies the cylinder group index and the rotor\npositions straight from the on-disk group and caches them without any\ncheck:\n\n\tucpi-\u003ec_cgx    = fs32_to_cpu(sb, ucg-\u003ecg_cgx);\n\tucpi-\u003ec_rotor  = fs32_to_cpu(sb, ucg-\u003ecg_rotor);\n\tucpi-\u003ec_frotor = fs32_to_cpu(sb, ucg-\u003ecg_frotor);\n\tucpi-\u003ec_irotor = fs32_to_cpu(sb, ucg-\u003ecg_irotor);\n\nThey are then used as indices during allocation and free:\n\n  - c_cgx indexes the cylinder summary array as\n    UFS_SB(sb)-\u003efs_cs(ucpi-\u003ec_cgx), so a value past s_ncg writes a 32\n    bit count outside the s_csp allocation.\n\n  - c_frotor becomes a bitmap scan start, start = c_frotor \u003e\u003e 3, and\n    then length = ((s_fpg + 7) \u003e\u003e 3) - start. A start beyond the block\n    bitmap wraps the unsigned length to a huge value, so ubh_scanc()\n    walks far past the cylinder group buffers. c_irotor drives the\n    inode bitmap the same way.\n\nA crafted image can set any of these freely, turning an ordinary\nallocation into an out of bounds access.\n\nReject a cylinder group whose recorded index does not match the group\nbeing read, or whose rotors fall outside the group, before the metadata\nis cached. Valid filesystems keep cg_cgx equal to the group number and\nthe rotors within the group, so only malformed images are rejected.","modified":"2026-09-27T05:34:32Z","published":"2026-09-25T11:17:19Z","upstream":["CVE-2026-97926"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97926"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.157.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-104430.json"}}],"schema_version":"1.9.0"}