{"id":"CVE-2026-64269","state":"PUBLISHED","title":"RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg","description":"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 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).","publishedAt":"2026-07-25T08:49:16.946Z","updatedAt":"2026-08-23T12:45:35.835Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"a35b7a8728a53ddc80b323970689fa5985816836","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"68c09762172f6224e9ddf9b0a60bacbb36e443eb","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"6cada540150894e81042a0ae0c796a21a9a877da","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"2912f3d40355dabc08fdbaaf2764d02445fe88dc","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"6f40246f4312fdbab5a13cc440adebf95eb2aa66","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"5a45d0aa1fa50a333ce5763ade744e2d89838667","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"da3e44add94b05dfde56f898421922f5cf35705f","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"963af8d97a8c6a117134a8d0db1415e0489200b1","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/ulp/rtrs/rtrs-srv.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.8","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/ulp/rtrs/rtrs-srv.c"]}],"references":["https://git.kernel.org/stable/c/a35b7a8728a53ddc80b323970689fa5985816836","https://git.kernel.org/stable/c/68c09762172f6224e9ddf9b0a60bacbb36e443eb","https://git.kernel.org/stable/c/6cada540150894e81042a0ae0c796a21a9a877da","https://git.kernel.org/stable/c/2912f3d40355dabc08fdbaaf2764d02445fe88dc","https://git.kernel.org/stable/c/6f40246f4312fdbab5a13cc440adebf95eb2aa66","https://git.kernel.org/stable/c/5a45d0aa1fa50a333ce5763ade744e2d89838667","https://git.kernel.org/stable/c/da3e44add94b05dfde56f898421922f5cf35705f","https://git.kernel.org/stable/c/963af8d97a8c6a117134a8d0db1415e0489200b1"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64269.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64269","state":"PUBLISHED","datePublished":"2026-07-25T08:49:16.946Z","dateUpdated":"2026-08-23T12:45:35.835Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.775Z"},"containers":{"cna":{"title":"RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg","descriptions":[{"lang":"en","value":"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 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)."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"a35b7a8728a53ddc80b323970689fa5985816836","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"68c09762172f6224e9ddf9b0a60bacbb36e443eb","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"6cada540150894e81042a0ae0c796a21a9a877da","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"2912f3d40355dabc08fdbaaf2764d02445fe88dc","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"6f40246f4312fdbab5a13cc440adebf95eb2aa66","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"5a45d0aa1fa50a333ce5763ade744e2d89838667","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"da3e44add94b05dfde56f898421922f5cf35705f","versionType":"git"},{"version":"9cb837480424e78ed585376f944088246685aec3","status":"affected","lessThan":"963af8d97a8c6a117134a8d0db1415e0489200b1","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/ulp/rtrs/rtrs-srv.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.8","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/ulp/rtrs/rtrs-srv.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/a35b7a8728a53ddc80b323970689fa5985816836"},{"url":"https://git.kernel.org/stable/c/68c09762172f6224e9ddf9b0a60bacbb36e443eb"},{"url":"https://git.kernel.org/stable/c/6cada540150894e81042a0ae0c796a21a9a877da"},{"url":"https://git.kernel.org/stable/c/2912f3d40355dabc08fdbaaf2764d02445fe88dc"},{"url":"https://git.kernel.org/stable/c/6f40246f4312fdbab5a13cc440adebf95eb2aa66"},{"url":"https://git.kernel.org/stable/c/5a45d0aa1fa50a333ce5763ade744e2d89838667"},{"url":"https://git.kernel.org/stable/c/da3e44add94b05dfde56f898421922f5cf35705f"},{"url":"https://git.kernel.org/stable/c/963af8d97a8c6a117134a8d0db1415e0489200b1"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","baseScore":9.1,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - RTRS accepts network connections over routable RDMA transports including RoCE and iWARP, and the malicious descriptor is supplied by a remote peer.\nAC:L - The peer directly controls the descriptor length and destination buffer; no race, timing, or victim-controlled state is required in no-IOMMU, passthrough, or software-RDMA deployments.\nPR:N - The handshake validates protocol fields but performs no credential, capability, or authentication check before publishing chunk rkeys and accepting I/O requests.\nUI:N - After connecting, the attacker can submit the crafted RDMA READ request without any victim action.\nS:U - The vulnerable RTRS module and affected host memory remain within the kernel's security authority; a translating IOMMU prevents rather than permits crossing its isolation boundary.\nC:H - The PD-wide local DMA key does not constrain the attacker-supplied transfer length, permitting a broad out-of-bounds read of adjacent host memory that is returned to the peer.\nI:N - The malformed operation reads server memory and writes it only to the peer's registered destination; it provides no server-side memory-write primitive.\nA:H - Software-RDMA can CPU-copy through invalid pages and oops or crash, while hardware or IOMMU faults can abort paths. An unauthenticated peer can trigger the condition repeatedly."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-23T12:45:35.835Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"5.10.266"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}