{"id":"CVE-2026-46133","title":"RDMA/rxe: Reject unknown opcodes before ICRC processing","summary":"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…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 318787fa7193bd79691f2ebce4e80cb6abd0faef","Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 6a79b1ea0fcb2c998fda6a793050f66146e9cc42","Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 599cfdf44c1701c581cd4a21f1e1e03f8dc3840b","Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < e3dc3a2fb05f4ed49c7f20594c4c52350d032189","Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < f8ee926431a7bbec2b10c1290664af2cb290b983","Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 006a3a5f75345c6a0dbf13fd3ee01406e93b6733","Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 6fa18025e5782afff91415fd5217b39c1e4837d7","Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 4c6f86d85d03cdb33addce86aa69aa795ca6c47a","Linux 4.8"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T15:20:11.447368Z"},"published":"2026-05-28","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:31:04.376Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-46133","references":[{"url":"https://git.kernel.org/stable/c/318787fa7193bd79691f2ebce4e80cb6abd0faef"},{"url":"https://git.kernel.org/stable/c/6a79b1ea0fcb2c998fda6a793050f66146e9cc42"},{"url":"https://git.kernel.org/stable/c/599cfdf44c1701c581cd4a21f1e1e03f8dc3840b"},{"url":"https://git.kernel.org/stable/c/e3dc3a2fb05f4ed49c7f20594c4c52350d032189"},{"url":"https://git.kernel.org/stable/c/f8ee926431a7bbec2b10c1290664af2cb290b983"},{"url":"https://git.kernel.org/stable/c/006a3a5f75345c6a0dbf13fd3ee01406e93b6733"},{"url":"https://git.kernel.org/stable/c/6fa18025e5782afff91415fd5217b39c1e4837d7"},{"url":"https://git.kernel.org/stable/c/4c6f86d85d03cdb33addce86aa69aa795ca6c47a"}],"tags":["cve.org"],"epss":0.00574,"epssPercentile":0.46227,"ingestedAt":"2026-10-16T17:24:46.709Z","slug":"CVE-2026-46133","body":"## Overview\n\nIn 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->paylen < header_size(pkt) + bth_pad(pkt) + RXE_ICRC_SIZE\n\nwhere header_size(pkt) expands to rxe_opcode[pkt->opcode].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->paylen < 0 + bth_pad(pkt) + RXE_ICRC_SIZE\n\nwhich does not constrain pkt->paylen enough.  rxe_icrc_hdr() then computes\n\n    rxe_opcode[pkt->opcode].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.\n\n## Affected\n\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 318787fa7193bd79691f2ebce4e80cb6abd0faef`\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 6a79b1ea0fcb2c998fda6a793050f66146e9cc42`\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 599cfdf44c1701c581cd4a21f1e1e03f8dc3840b`\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < e3dc3a2fb05f4ed49c7f20594c4c52350d032189`\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < f8ee926431a7bbec2b10c1290664af2cb290b983`\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 006a3a5f75345c6a0dbf13fd3ee01406e93b6733`\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 6fa18025e5782afff91415fd5217b39c1e4837d7`\n- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 4c6f86d85d03cdb33addce86aa69aa795ca6c47a`\n- `Linux 4.8`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}