io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries

{
  "id": "3ef209822c982beb858afca70cc61e50a1ce750e601dcd49f336cf8bf748cc67",
  "url": "https://osv.dev/vulnerability/CVE-2026-53191",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries When a bundle recv retries inside io_recv_finish(), the merge logic OR the saved cflags from the previous iteration with the cflags returned by the new iteration: cflags = req->cqe.flags | (cflags & CQE_F_MASK); Bits listed in CQE_F_MASK are inherited from the new iteration, and all other bits (notably IORING_CQE_F_BUFFER and the buffer ID) come from the saved cflags. Before this change CQE_F_MASK covered only IORING_CQE_F_SOCK_NONEMPTY and IORING_CQE_F_MORE. When using provided buffer rings (IOU_PBUF_RING_INC) with incremental mode, and bundle recv, io_kbuf_inc_commit() can leave the head ring entry partially consumed, __io_put_kbufs() then sets IORING_CQE_F_BUF_MORE on the returned cflags so userspace knows the buffer ID will be reused for subsequent completions. Because IORING_CQE_F_BUF_MORE was not in CQE_F_MASK, the merge above silently dropped it whenever the final retry iteration partially consumed the buffer, and the subsequent req->cqe.flags = cflags & ~CQE_F_MASK save would have left a stale IORING_CQE_F_BUF_MORE in the carried-over cflags had one been present. Userspace would then wrongfully advance it ring head past an entry the kernel still uses. Add IORING_CQE_F_BUF_MORE to CQE_F_MASK so it is both inherited from the new iteration into the user-visible CQE and stripped from the saved cflags between iterations.",
    "evidence": "osv:CVE-2026-53191",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.94",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.36",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.13",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-53191",
      "aliases": [
        "CVE-2026-53191"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "ae98dbf43d755b4e111fcd086e53939bef3e9a1a"
                },
                {
                  "fixed": "f40570fda3f3a1f96aeaa4aef665ba274b2810b5"
                },
                {
                  "fixed": "0bbc9481f970b0b4ddb08cfa464db1cc93b74b56"
                },
                {
                  "fixed": "4973232a67e4137ab9399f504f7f2bdd847f96d2"
                },
                {
                  "fixed": "ed46f39c47eb5530a9c161481a2080d3a869cfaf"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53191.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.12.0"
                },
                {
                  "fixed": "6.12.94"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.36"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.13"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53191.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:51.103088481Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0bbc9481f970b0b4ddb08cfa464db1cc93b74b56",
        "https://git.kernel.org/stable/c/4973232a67e4137ab9399f504f7f2bdd847f96d2",
        "https://git.kernel.org/stable/c/ed46f39c47eb5530a9c161481a2080d3a869cfaf",
        "https://git.kernel.org/stable/c/f40570fda3f3a1f96aeaa4aef665ba274b2810b5",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53191.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-53191",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53191.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-53191",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519929,
  "published_at": "2026-06-25T08:39:03.052+00:00"
}