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CVE-2026-89530 (GCVE-0-2026-89530)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:44 – Updated: 2026-09-13 06:30
VLAI
Title
svcrdma: Reject inline replies that overflow the pull-up buffer
Summary
In the Linux kernel, the following vulnerability has been resolved: svcrdma: Reject inline replies that overflow the pull-up buffer An RPC-over-RDMA client can request a reply, such as an NFS READ payload, without providing a Write list or a Reply chunk to carry it. When such a reply needs more scatter/gather entries than the device's Send Queue supports, svc_rdma_pull_up_needed() selects pull-up and svc_rdma_pull_up_reply_msg() linearizes the whole reply into sctxt->sc_xprt_buf. That buffer is only sc_max_req_size bytes, while the reply on this path is bounded only by the client's request, so svc_rdma_xb_linearize() copies past the end of the buffer and corrupts adjacent slab memory. The oversized length is then stored in sc_sges[0].length and posted, so the device also reads beyond the mapped region. The SGE-exhaustion branch is the only pull-up path that can exceed the buffer: the threshold branch pulls up only replies smaller than RPCRDMA_PULLUP_THRESH, and replies that fit the device's SGE budget are sent directly without linearization. Make svc_rdma_pull_up_needed() report -E2BIG when the reply it would pull up cannot fit sc_max_req_size, and fail the request with ERR_CHUNK as RFC 8166 Section 4.5.3 directs rather than dropping the connection. The helper no longer answers a simple yes/no question: it now reports pull-up, no pull-up, or -E2BIG for a reply too large to linearize. Rename svc_rdma_pull_up_needed() to svc_rdma_check_pull_up() so its name no longer implies a boolean predicate.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e248aa7be86e8179f20ac0931774ecd746f3f5bf , < fcd91b9957462d398792201c239dffaeff1cc8b2 (git)
Affected: e248aa7be86e8179f20ac0931774ecd746f3f5bf , < 1949dd1576f7a8aa161b1330c6125df9d53046d5 (git)
Affected: e248aa7be86e8179f20ac0931774ecd746f3f5bf , < 8ec60eb51fae37cd3d334ff26e4a7d6fb21ff7cf (git)
Affected: e248aa7be86e8179f20ac0931774ecd746f3f5bf , < 0fbe20dfe74b783d255bf389a6ea77aa25dc7860 (git)
Affected: 9b65b18f817d9ada2bf67351f24bdcce6789a0bb (git)
Affected: d564356e1919d1178568c19af410cfc1a9076663 (git)
Affected: 4.19.22 , < 4.20 (semver)
Affected: 4.20.9 , < 4.21 (semver)
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Linux Linux Affected: 5.0
Unaffected: 0 , < 5.0 (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Reject inline replies that overflow the pull-up buffer\n\nAn RPC-over-RDMA client can request a reply, such as an NFS READ\npayload, without providing a Write list or a Reply chunk to carry\nit. When such a reply needs more scatter/gather entries than the\ndevice\u0027s Send Queue supports, svc_rdma_pull_up_needed() selects\npull-up and svc_rdma_pull_up_reply_msg() linearizes the whole\nreply into sctxt-\u003esc_xprt_buf. That buffer is only sc_max_req_size\nbytes, while the reply on this path is bounded only by the client\u0027s\nrequest, so svc_rdma_xb_linearize() copies past the end of the\nbuffer and corrupts adjacent slab memory. The oversized length is\nthen stored in sc_sges[0].length and posted, so the device also\nreads beyond the mapped region.\n\nThe SGE-exhaustion branch is the only pull-up path that can exceed\nthe buffer: the threshold branch pulls up only replies smaller\nthan RPCRDMA_PULLUP_THRESH, and replies that fit the device\u0027s SGE\nbudget are sent directly without linearization. Make\nsvc_rdma_pull_up_needed() report -E2BIG when the reply it would\npull up cannot fit sc_max_req_size, and fail the request with\nERR_CHUNK as RFC 8166 Section 4.5.3 directs rather than dropping\nthe connection.\n\nThe helper no longer answers a simple yes/no question: it now\nreports pull-up, no pull-up, or -E2BIG for a reply too large to\nlinearize. Rename svc_rdma_pull_up_needed() to\nsvc_rdma_check_pull_up() so its name no longer implies a boolean\npredicate."
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              "value": "AV:N - svcrdma is nfsd\u0027s RPC-over-RDMA server transport; a remote NFS/RDMA client reaches svc_rdma_sendto over InfiniBand, RoCE, or iWARP, including IP-routable RoCEv2/iWARP and Soft-RoCE, so this is a network attack.\nAC:L - The attacker fully controls omitting the Write list and Reply chunk and the NFS READ size; with the default 4096-byte pull-up buffer and ~5 Send SGEs, a multi-page inline READ deterministically takes the SGE-exhaustion pull-up path and overflows, with no race or uncontrollable layout.\nPR:N - RDMA-CM accept has no credential check, and AUTH_NULL/AUTH_UNIX need no real account; default NFS exports accept those flavors, so a fabric peer can drive a large READ reply without local or init-namespace privileges.\nUI:N - Exploitation requires only attacker-sent RPC-over-RDMA Calls that elicit a large inline reply; no victim mount, click, or other user action is needed beyond nfsd already listening on RDMA.\nS:U - The kmalloc overflow and oversized RDMA Send stay inside the host kernel\u0027s security authority; this is not a VM, IOMMU, or sandbox escape.\nC:H - svc_rdma_xb_linearize() copies past kmalloc sc_xprt_buf, then the inflated sc_sges[0].length is posted with the PD local DMA lkey, so the device reads adjacent kernel memory onto the wire; the heap smash is also leveragable for disclosure.\nI:H - The unbounded memcpy is a heap out-of-bounds write of attacker-influenced NFS READ payload into adjacent slab objects, enabling corruption of neighboring kernel state and control-flow hijacking.\nA:H - Overflowing a 4KB send buffer by up to the NFS/RDMA max payload smashes adjacent slab and can oops or panic, and posting an SGE longer than the DMA mapping can also fault the device or kernel."
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        "shortName": "Linux"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89530",
    "datePublished": "2026-09-11T19:44:10.024Z",
    "dateReserved": "2026-09-11T19:38:34.719Z",
    "dateUpdated": "2026-09-13T06:30:27.209Z",
    "state": "PUBLISHED"
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      "date": "2026-09-16",
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That buffer is only sc_max_req_size\\nbytes, while the reply on this path is bounded only by the client\u0027s\\nrequest, so svc_rdma_xb_linearize() copies past the end of the\\nbuffer and corrupts adjacent slab memory. The oversized length is\\nthen stored in sc_sges[0].length and posted, so the device also\\nreads beyond the mapped region.\\n\\nThe SGE-exhaustion branch is the only pull-up path that can exceed\\nthe buffer: the threshold branch pulls up only replies smaller\\nthan RPCRDMA_PULLUP_THRESH, and replies that fit the device\u0027s SGE\\nbudget are sent directly without linearization. Make\\nsvc_rdma_pull_up_needed() report -E2BIG when the reply it would\\npull up cannot fit sc_max_req_size, and fail the request with\\nERR_CHUNK as RFC 8166 Section 4.5.3 directs rather than dropping\\nthe connection.\\n\\nThe helper no longer answers a simple yes/no question: it now\\nreports pull-up, no pull-up, or -E2BIG for a reply too large to\\nlinearize. Rename svc_rdma_pull_up_needed() to\\nsvc_rdma_check_pull_up() so its name no longer implies a boolean\\npredicate.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/sunrpc/xprtrdma/svc_rdma_sendto.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"e248aa7be86e8179f20ac0931774ecd746f3f5bf\",\"lessThan\":\"fcd91b9957462d398792201c239dffaeff1cc8b2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"e248aa7be86e8179f20ac0931774ecd746f3f5bf\",\"lessThan\":\"1949dd1576f7a8aa161b1330c6125df9d53046d5\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"e248aa7be86e8179f20ac0931774ecd746f3f5bf\",\"lessThan\":\"8ec60eb51fae37cd3d334ff26e4a7d6fb21ff7cf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"e248aa7be86e8179f20ac0931774ecd746f3f5bf\",\"lessThan\":\"0fbe20dfe74b783d255bf389a6ea77aa25dc7860\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"9b65b18f817d9ada2bf67351f24bdcce6789a0bb\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"d564356e1919d1178568c19af410cfc1a9076663\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4.19.22\",\"lessThan\":\"4.20\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"4.20.9\",\"lessThan\":\"4.21\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/sunrpc/xprtrdma/svc_rdma_sendto.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.0\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.0\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.109\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0fbe20dfe74b783d255bf389a6ea77aa25dc7860\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1949dd1576f7a8aa161b1330c6125df9d53046d5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8ec60eb51fae37cd3d334ff26e4a7d6fb21ff7cf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/fcd91b9957462d398792201c239dffaeff1cc8b2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-13T06:49:57+00:00",
      "cve": "CVE-2026-89530",
      "id": "CVE-2026-89530",
      "initial_release_date": "2026-09-11T19:44:10.024000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: Memory corruption in svcrdma due to oversized network replies",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89530.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "critical",
      "current_release_date": "2026-09-16T15:37:17Z",
      "cve": "CVE-2026-89530",
      "id": "CVE-2026-89530",
      "initial_release_date": "2026-09-12T16:26:40Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89530",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89530.json",
      "version": "3"
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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