{"id":"AZL-83699","summary":"CVE-2026-31570 affecting package kernel for versions less than 6.6.134.1-2","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: gw: fix OOB heap access in cgw_csum_crc8_rel()\n\ncgw_csum_crc8_rel() correctly computes bounds-safe indices via calc_idx():\n\n    int from = calc_idx(crc8-\u003efrom_idx, cf-\u003elen);\n    int to   = calc_idx(crc8-\u003eto_idx,   cf-\u003elen);\n    int res  = calc_idx(crc8-\u003eresult_idx, cf-\u003elen);\n\n    if (from \u003c 0 || to \u003c 0 || res \u003c 0)\n        return;\n\nHowever, the loop and the result write then use the raw s8 fields directly\ninstead of the computed variables:\n\n    for (i = crc8-\u003efrom_idx; ...)        /* BUG: raw negative index */\n    cf-\u003edata[crc8-\u003eresult_idx] = ...;    /* BUG: raw negative index */\n\nWith from_idx = to_idx = result_idx = -64 on a 64-byte CAN FD frame,\ncalc_idx(-64, 64) = 0 so the guard passes, but the loop iterates with\ni = -64, reading cf-\u003edata[-64], and the write goes to cf-\u003edata[-64].\nThis write might end up to 56 (7.0-rc) or 40 (\u003c= 6.19) bytes before the\nstart of the canfd_frame on the heap.\n\nThe companion function cgw_csum_xor_rel() uses `from`/`to`/`res`\ncorrectly throughout; fix cgw_csum_crc8_rel() to match.\n\nConfirmed with KASAN on linux-7.0-rc2:\n  BUG: KASAN: slab-out-of-bounds in cgw_csum_crc8_rel+0x515/0x5b0\n  Read of size 1 at addr ffff8880076619c8 by task poc_cgw_oob/62\n\nTo configure the can-gw crc8 checksums CAP_NET_ADMIN is needed.","modified":"2026-08-28T17:47:34.446816909Z","published":"2026-04-24T15:16:31Z","upstream":["CVE-2026-31570"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31570"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.134.1-2"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-83699.json"}}],"schema_version":"1.9.0"}