CriticalFix available

nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte queue->pdu union, then computes the remaining payload length as queue->left = hdr->hlen - queue->offset + hdgst; and reads that many more bytes into &queue->pdu + queue->offset, without ever bounding the result against sizeof(queue->pdu). A struct nvme_tcp_icreq_pdu is itself 128 bytes, exactly the size of the union. Once a header digest has been negotiated (hdgst = 4), a second ICReq passes the hlen == nvmet_tcp_pdu_size() check but yields queue->left = 128 - 8 + 4 = 124, so bytes 8..132 are written into the 128-byte buffer -- 4 bytes past its end, over queue->hdr_digest and queue->data_digest. Those bytes are attacker-controlled (an ICReq carries no digest), and the duplicate ICReq is only rejected later, after the overflow. A remote unauthenticated host can thus corrupt kernel memory adjacent to the receive buffer. Reject any PDU whose declared length would read past the end of queue->pdu before the second recv.

Products: Kernel
Affected versions: Not specified
Fixed versions: 5.10.270, 5.15.221, 6.1.188, 6.12.110, 6.18.51, 6.6.157, 7.2.5
CVEs: CVE-2026-89969
Confirmed fixed CVEs: Not specified
Updated in this feed: 4 Nov 2026, 02:19 UTC · Revision 1

Source evidence

nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU

core-osv · Original source

Published 16 Sept 2026, 10:32 UTC

osv:CVE-2026-89969

Kernel

Fixed versions: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, 7.2.5

Complete source record

{
  "id": "edf127812a062af5853ba4ce5e03554b5b256072075d8720b50e8d83660b409b",
  "url": "https://osv.dev/vulnerability/CVE-2026-89969",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte queue->pdu union, then computes the remaining payload length as queue->left = hdr->hlen - queue->offset + hdgst; and reads that many more bytes into &queue->pdu + queue->offset, without ever bounding the result against sizeof(queue->pdu). A struct nvme_tcp_icreq_pdu is itself 128 bytes, exactly the size of the union. Once a header digest has been negotiated (hdgst = 4), a second ICReq passes the hlen == nvmet_tcp_pdu_size() check but yields queue->left = 128 - 8 + 4 = 124, so bytes 8..132 are written into the 128-byte buffer -- 4 bytes past its end, over queue->hdr_digest and queue->data_digest. Those bytes are attacker-controlled (an ICReq carries no digest), and the duplicate ICReq is only rejected later, after the overflow. A remote unauthenticated host can thus corrupt kernel memory adjacent to the receive buffer. Reject any PDU whose declared length would read past the end of queue->pdu before the second recv.",
    "evidence": "osv:CVE-2026-89969",
    "products": [
      {
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      "modified": "2026-10-28T02:30:32.273553912Z",
      "provider": "osv",
      "references": [
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        "https://git.kernel.org/stable/c/3a385e0c39efbe34db8edd95900c123113ae3450",
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        "https://git.kernel.org/stable/c/d95d342bc0ea82dc79e6362b2f1f997431750e4c",
        "https://git.kernel.org/stable/c/dbc4acbdb3ca8c81441368ad7409b8f77d4de8f6",
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      "provider_metadata": {
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  "source_id": "core-osv",
  "document_id": 499590,
  "published_at": "2026-09-16T10:32:49.603+00:00"
}