{"id":"CVE-2026-72464","title":"xprtrdma: Repost Receive buffers for malformed replies","summary":"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's Receive count for\nevery completion before it dispatches a succes…","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 >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < ef6fb8a5c521f1a07f85202d13e8f2898f247362","Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < 4322fd9645ee769ad29ce5caea74a1cd9b17269d","Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < 19fae02b272ee4bcdfb5db57f402d28f1697167a","Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < 007b4da2f38dcc16a13265416f4ca9f179bab610","Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < d7c531ab477ae94fd03771d707fd29c787408039","Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5","Linux 3791c5982ba1eebf2900ee7ca7b9a89619c26d54","Linux >= 5.4.13 < 5.5","Linux 5.5"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T18:50:20.084963Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:25.140Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72464","references":[{"url":"https://git.kernel.org/stable/c/ef6fb8a5c521f1a07f85202d13e8f2898f247362"},{"url":"https://git.kernel.org/stable/c/4322fd9645ee769ad29ce5caea74a1cd9b17269d"},{"url":"https://git.kernel.org/stable/c/19fae02b272ee4bcdfb5db57f402d28f1697167a"},{"url":"https://git.kernel.org/stable/c/007b4da2f38dcc16a13265416f4ca9f179bab610"},{"url":"https://git.kernel.org/stable/c/d7c531ab477ae94fd03771d707fd29c787408039"},{"url":"https://git.kernel.org/stable/c/abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5"}],"tags":["cve.org"],"epss":0.00675,"epssPercentile":0.51234,"ingestedAt":"2026-10-16T19:46:24.393Z","slug":"CVE-2026-72464","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nxprtrdma: Repost Receive buffers for malformed replies\n\nrpcrdma_wc_receive() decrements the transport's 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's 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's 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's 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->rb_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.\n\n## Affected\n\n- `Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < ef6fb8a5c521f1a07f85202d13e8f2898f247362`\n- `Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < 4322fd9645ee769ad29ce5caea74a1cd9b17269d`\n- `Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < 19fae02b272ee4bcdfb5db57f402d28f1697167a`\n- `Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < 007b4da2f38dcc16a13265416f4ca9f179bab610`\n- `Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < d7c531ab477ae94fd03771d707fd29c787408039`\n- `Linux >= 2ae50ad68cd79224198b525f7bd645c9da98b6ff < abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5`\n- `Linux 3791c5982ba1eebf2900ee7ca7b9a89619c26d54`\n- `Linux >= 5.4.13 < 5.5`\n- `Linux 5.5`\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":[]}