{"id":"AZL-89102","summary":"CVE-2026-46133 affecting package kernel for versions less than 6.6.141.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: Reject unknown opcodes before ICRC processing\n\nEven after applying commit 7244491dab34 (\"RDMA/rxe: Validate pad and ICRC\nbefore payload_size() in rxe_rcv\"), a single unauthenticated UDP packet\ncan still trigger panic.  That patch handled payload_size() underflow only\nfor valid opcodes with short packets, not for packets carrying an unknown\nopcode.  The unknown-opcode OOB read described below predates that commit\nand reaches back to the initial Soft RoCE driver.\n\nThe check added there reads\n\n    pkt-\u003epaylen \u003c header_size(pkt) + bth_pad(pkt) + RXE_ICRC_SIZE\n\nwhere header_size(pkt) expands to rxe_opcode[pkt-\u003eopcode].length.  The\nrxe_opcode[] array has 256 entries but is only populated for defined IB\nopcodes; any other entry (for example opcode 0xff) is zero-initialized, so\nlength == 0 and the check degenerates to\n\n    pkt-\u003epaylen \u003c 0 + bth_pad(pkt) + RXE_ICRC_SIZE\n\nwhich does not constrain pkt-\u003epaylen enough.  rxe_icrc_hdr() then computes\n\n    rxe_opcode[pkt-\u003eopcode].length - RXE_BTH_BYTES\n\nwhich underflows when length == 0 and passes a huge value to rxe_crc32(),\ncausing an out-of-bounds read of the skb payload.\n\nReproduced on v7.0-rc7 with that fix applied, QEMU/KVM with\nCONFIG_RDMA_RXE=y and CONFIG_KASAN=y, after\n\n    rdma link add rxe0 type rxe netdev eth0\n\nA single 48-byte UDP packet to port 4791 with BTH opcode=0xff and\nQPN=IB_MULTICAST_QPN triggers:\n\n    BUG: KASAN: slab-out-of-bounds in crc32_le+0x115/0x170\n    Read of size 1 at addr ...\n    The buggy address is located 0 bytes to the right of\n     allocated 704-byte region\n    Call Trace:\n     crc32_le+0x115/0x170\n     rxe_icrc_hdr.isra.0+0x226/0x300\n     rxe_icrc_check+0x13f/0x3a0\n     rxe_rcv+0x6e1/0x16e0\n     rxe_udp_encap_recv+0x20a/0x320\n     udp_queue_rcv_one_skb+0x7ed/0x12c0\n\nSubsequent packets with the same shape fault on unmapped memory and panic\nthe kernel.  The trigger requires only module load and \"rdma link add\"; no\nQP, no connection, and no authentication.\n\nFix this by rejecting packets whose opcode has no rxe_opcode[] entry,\ndetected via the zero mask or zero length, before any length arithmetic\nruns.","modified":"2026-08-28T17:48:10.278524145Z","published":"2026-05-28T10:16:28Z","upstream":["CVE-2026-46133"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-46133"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.141.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-89102.json"}}],"schema_version":"1.9.0"}