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FKIE_CVE-2026-72464

Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-08-17 06:19
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: xprtrdma: Repost Receive buffers for malformed replies rpcrdma_wc_receive() decrements the transport's Receive count for every completion before it dispatches a successful Receive to rpcrdma_reply_handler(). The handler must post a replacement Receive WR before returning unless ownership of the rep has moved elsewhere, as on the backchannel path. Commit 2ae50ad68cd7 ("xprtrdma: Close window between waking RPC senders and posting Receives") moved the Receive refill out of rpcrdma_wc_receive(), where it had run ahead of every reply, into rpcrdma_reply_handler() so that the responder's credit grant could be parsed before reposting. The bad-version and short-reply exits never reach that refill: they recycle the rep and return without calling rpcrdma_post_recvs(). A remote peer can therefore drain the client's posted Receive queue by sending a sustained stream of replies that are shorter than the fixed transport header or that carry an unrecognized RPC/RDMA version. Each such reply consumes one posted Receive without replacing it. Once the queue empties, the peer's next Send finds no posted Receive and the transport stalls until reconnect. Route both malformed-reply exits through the shared repost tail after recycling the rep, refilling against buf->rb_credits, the most recent accepted credit grant. Neither exit updates the congestion window, so RPCs admitted under the previous grant remain in flight awaiting replies. A smaller refill target would let a stream of malformed replies ratchet the posted Receive count down to the batch floor while the congestion window still admits rb_credits RPCs; a burst of valid replies to those RPCs could then overrun the posted Receives, and because the client connects with rnr_retry_count of zero, a single RNR NAK terminates the connection. Refilling against rb_credits also restores the target that applied to malformed replies before commit 2ae50ad68cd7 ("xprtrdma: Close window between waking RPC senders and posting Receives") when rpcrdma_post_recvs() computed it from rb_credits internally. rb_credits is at least one from connection establishment onward, so the repost path always keeps Receives posted.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/007b4da2f38dcc16a13265416f4ca9f179bab610
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/19fae02b272ee4bcdfb5db57f402d28f1697167a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4322fd9645ee769ad29ce5caea74a1cd9b17269d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d7c531ab477ae94fd03771d707fd29c787408039
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ef6fb8a5c521f1a07f85202d13e8f2898f247362
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sunrpc/xprtrdma/rpc_rdma.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ef6fb8a5c521f1a07f85202d13e8f2898f247362",
              "status": "affected",
              "version": "2ae50ad68cd79224198b525f7bd645c9da98b6ff",
              "versionType": "git"
            },
            {
              "lessThan": "4322fd9645ee769ad29ce5caea74a1cd9b17269d",
              "status": "affected",
              "version": "2ae50ad68cd79224198b525f7bd645c9da98b6ff",
              "versionType": "git"
            },
            {
              "lessThan": "19fae02b272ee4bcdfb5db57f402d28f1697167a",
              "status": "affected",
              "version": "2ae50ad68cd79224198b525f7bd645c9da98b6ff",
              "versionType": "git"
            },
            {
              "lessThan": "007b4da2f38dcc16a13265416f4ca9f179bab610",
              "status": "affected",
              "version": "2ae50ad68cd79224198b525f7bd645c9da98b6ff",
              "versionType": "git"
            },
            {
              "lessThan": "d7c531ab477ae94fd03771d707fd29c787408039",
              "status": "affected",
              "version": "2ae50ad68cd79224198b525f7bd645c9da98b6ff",
              "versionType": "git"
            },
            {
              "lessThan": "abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5",
              "status": "affected",
              "version": "2ae50ad68cd79224198b525f7bd645c9da98b6ff",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "3791c5982ba1eebf2900ee7ca7b9a89619c26d54",
              "versionType": "git"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.13",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sunrpc/xprtrdma/rpc_rdma.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.5"
            },
            {
              "lessThan": "5.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxprtrdma: Repost Receive buffers for malformed replies\n\nrpcrdma_wc_receive() decrements the transport\u0027s Receive count for\nevery completion before it dispatches a successful Receive to\nrpcrdma_reply_handler(). The handler must post a replacement\nReceive WR before returning unless ownership of the rep has moved\nelsewhere, as on the backchannel path.\n\nCommit 2ae50ad68cd7 (\"xprtrdma: Close window between waking RPC\nsenders and posting Receives\") moved the Receive refill out of\nrpcrdma_wc_receive(), where it had run ahead of every reply, into\nrpcrdma_reply_handler() so that the responder\u0027s credit grant could\nbe parsed before reposting. The bad-version and short-reply exits\nnever reach that refill: they recycle the rep and return without\ncalling rpcrdma_post_recvs().\n\nA remote peer can therefore drain the client\u0027s posted Receive\nqueue by sending a sustained stream of replies that are shorter\nthan the fixed transport header or that carry an unrecognized\nRPC/RDMA version. Each such reply consumes one posted Receive\nwithout replacing it. Once the queue empties, the peer\u0027s next\nSend finds no posted Receive and the transport stalls until\nreconnect.\n\nRoute both malformed-reply exits through the shared repost tail\nafter recycling the rep, refilling against buf-\u003erb_credits, the\nmost recent accepted credit grant. Neither exit updates the\ncongestion window, so RPCs admitted under the previous grant\nremain in flight awaiting replies. A smaller refill target would\nlet a stream of malformed replies ratchet the posted Receive count\ndown to the batch floor while the congestion window still admits\nrb_credits RPCs; a burst of valid replies to those RPCs could then\noverrun the posted Receives, and because the client connects with\nrnr_retry_count of zero, a single RNR NAK terminates the\nconnection. Refilling against rb_credits also restores the target\nthat applied to malformed replies before commit 2ae50ad68cd7\n(\"xprtrdma: Close window between waking RPC senders and posting\nReceives\") when rpcrdma_post_recvs() computed it from rb_credits\ninternally. rb_credits is at least one from connection\nestablishment onward, so the repost path always keeps Receives\nposted."
    }
  ],
  "id": "CVE-2026-72464",
  "lastModified": "2026-08-17T06:19:14.157",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-15T06:22:20.400",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/007b4da2f38dcc16a13265416f4ca9f179bab610"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/19fae02b272ee4bcdfb5db57f402d28f1697167a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4322fd9645ee769ad29ce5caea74a1cd9b17269d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d7c531ab477ae94fd03771d707fd29c787408039"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ef6fb8a5c521f1a07f85202d13e8f2898f247362"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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