{"id":"CVE-2026-72464","state":"PUBLISHED","title":"xprtrdma: Repost Receive buffers for malformed replies","description":"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 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.","publishedAt":"2026-08-15T05:57:08.080Z","updatedAt":"2026-10-16T18:55:25.140Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"ef6fb8a5c521f1a07f85202d13e8f2898f247362","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"4322fd9645ee769ad29ce5caea74a1cd9b17269d","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"19fae02b272ee4bcdfb5db57f402d28f1697167a","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"007b4da2f38dcc16a13265416f4ca9f179bab610","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"d7c531ab477ae94fd03771d707fd29c787408039","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5","versionType":"git"},{"version":"3791c5982ba1eebf2900ee7ca7b9a89619c26d54","status":"affected","versionType":"git"},{"version":"5.4.13","status":"affected","lessThan":"5.5","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sunrpc/xprtrdma/rpc_rdma.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.5","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":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","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":["net/sunrpc/xprtrdma/rpc_rdma.c"]}],"references":["https://git.kernel.org/stable/c/ef6fb8a5c521f1a07f85202d13e8f2898f247362","https://git.kernel.org/stable/c/4322fd9645ee769ad29ce5caea74a1cd9b17269d","https://git.kernel.org/stable/c/19fae02b272ee4bcdfb5db57f402d28f1697167a","https://git.kernel.org/stable/c/007b4da2f38dcc16a13265416f4ca9f179bab610","https://git.kernel.org/stable/c/d7c531ab477ae94fd03771d707fd29c787408039","https://git.kernel.org/stable/c/abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72464.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72464","state":"PUBLISHED","datePublished":"2026-08-15T05:57:08.080Z","dateUpdated":"2026-10-16T18:55:25.140Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.933Z"},"containers":{"cna":{"title":"xprtrdma: Repost Receive buffers for malformed replies","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'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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"ef6fb8a5c521f1a07f85202d13e8f2898f247362","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"4322fd9645ee769ad29ce5caea74a1cd9b17269d","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"19fae02b272ee4bcdfb5db57f402d28f1697167a","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"007b4da2f38dcc16a13265416f4ca9f179bab610","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"d7c531ab477ae94fd03771d707fd29c787408039","versionType":"git"},{"version":"2ae50ad68cd79224198b525f7bd645c9da98b6ff","status":"affected","lessThan":"abc011ddaf1617e3e82d8a1e87daa7ddbfb9bac5","versionType":"git"},{"version":"3791c5982ba1eebf2900ee7ca7b9a89619c26d54","status":"affected","versionType":"git"},{"version":"5.4.13","status":"affected","lessThan":"5.5","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sunrpc/xprtrdma/rpc_rdma.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.5","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":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","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":["net/sunrpc/xprtrdma/rpc_rdma.c"]}],"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"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - Malicious or compromised NFS/RDMA server sends malformed RPC reply messages over an established RDMA connection; the kernel client processes them in rpcrdma_wc_receive()/rpcrdma_reply_handler() without any local access.\nAC:L - Remote server reliably triggers the bug by streaming replies shorter than the fixed RPC/RDMA header or carrying an unrecognized version; each consumes a posted Receive without reposting a replacement.\nPR:N - Attacker needs no credentials on the victim host, only the ability to act as the connected RDMA peer (e.g., a malicious or compromised NFS server the client has mounted).\nUI:N - Exploitation requires only an active NFS-over-RDMA client session; no additional victim action is needed beyond an existing mount/connection used for normal I/O.\nS:U - Impact is confined to SunRPC/RDMA transport availability on the NFS client; it does not cross VM, container, or kernel/user security boundaries.\nC:N - No memory corruption or out-of-bounds access occurs; short or bad-version replies are detected during header decode and the buffer is recycled without disclosing kernel data.\nI:N - The flaw only fails to repost Receive buffers after malformed replies; it does not corrupt memory, alter RPC payloads, or enable arbitrary kernel writes.\nA:H - Sustained malformed replies drain all posted Receives, stalling the transport until reconnect; a burst of valid replies can trigger RNR NAK and disconnect (rnr_retry_count=0), denying NFS/RDMA service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:44:30.706Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.13"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-72464","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T18:50:20.084963Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T18:55:25.140Z"}}]}}}