{"id":"CVE-2026-64269","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg\n\nWhen the server answers an RTRS READ, rdma_write_sg() builds the source\nscatter/gather entry for …","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg\n\nWhen the server answers an RTRS READ, rdma_write_sg() builds the source\nscatter/gather entry for …","severity":"critical","cvss":9.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","published":"2026-07-25","updated":"2026-07-27","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-64269","references":[{"url":"https://git.kernel.org/stable/c/2912f3d40355dabc08fdbaaf2764d02445fe88dc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5a45d0aa1fa50a333ce5763ade744e2d89838667","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/68c09762172f6224e9ddf9b0a60bacbb36e443eb","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6cada540150894e81042a0ae0c796a21a9a877da","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6f40246f4312fdbab5a13cc440adebf95eb2aa66","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/963af8d97a8c6a117134a8d0db1415e0489200b1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/da3e44add94b05dfde56f898421922f5cf35705f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00714,"epssPercentile":0.51602,"ingestedAt":"2026-07-27T06:16:49.749Z","slug":"CVE-2026-64269","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg\n\nWhen the server answers an RTRS READ, rdma_write_sg() builds the source\nscatter/gather entry for the IB_WR_RDMA_WRITE that returns data to the\npeer. Its length is taken directly from the wire descriptor:\n\n  plist->length = le32_to_cpu(id->rd_msg->desc[0].len);\n\nrd_msg points into the chunk buffer that the remote peer filled via\nRDMA-WRITE-WITH-IMM (rtrs_srv_rdma_done() -> process_io_req() ->\nprocess_read()), so desc[0].len is attacker-controlled and, before this\nchange, was only rejected when zero. The source address is the fixed\nchunk start (dma_addr[msg_id]) and the source lkey is the PD-wide\nlocal_dma_lkey, which is not tied to the chunk's MR mapping, so the verbs\nlayer does not constrain the transfer length to max_chunk_size. msg_id\nand off are bounded against queue_depth and max_chunk_size in\nrtrs_srv_rdma_done(), but desc[0].len is a separate field that was not\nchecked against the chunk size.\n\nA peer that advertises desc[0].len larger than max_chunk_size can make\nthe posted RDMA write read past the chunk's mapped region. The resulting\nbehaviour depends on the IOMMU configuration: with no IOMMU or in\npassthrough mode the read may extend into memory adjacent to the chunk\nand be returned to the peer, which can disclose host memory; with a\ntranslating IOMMU the out-of-range access is expected to fault and abort\nthe connection. In either case the transfer exceeds what the protocol\npermits and is driven by a remote peer.\n\nReject a descriptor length above max_chunk_size, mirroring the existing\noff >= max_chunk_size bound in rtrs_srv_rdma_done(). Legitimate clients\ndo not exceed it: the client sets desc[0].len to its MR length, which is\ncapped at the negotiated max_io_size (max_chunk_size - MAX_HDR_SIZE).\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":50,"depthScoreParts":{"impact":50.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}