FKIE_CVE-2026-53191

Vulnerability from fkie_nvd - Published: 2026-06-25 09:16 - Updated: 2026-06-30 14:44
Severity
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0bbc9481f970b0b4ddb08cfa464db1cc93b74b56
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4973232a67e4137ab9399f504f7f2bdd847f96d2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ed46f39c47eb5530a9c161481a2080d3a869cfaf
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f40570fda3f3a1f96aeaa4aef665ba274b2810b5
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/net.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f40570fda3f3a1f96aeaa4aef665ba274b2810b5",
              "status": "affected",
              "version": "ae98dbf43d755b4e111fcd086e53939bef3e9a1a",
              "versionType": "git"
            },
            {
              "lessThan": "0bbc9481f970b0b4ddb08cfa464db1cc93b74b56",
              "status": "affected",
              "version": "ae98dbf43d755b4e111fcd086e53939bef3e9a1a",
              "versionType": "git"
            },
            {
              "lessThan": "4973232a67e4137ab9399f504f7f2bdd847f96d2",
              "status": "affected",
              "version": "ae98dbf43d755b4e111fcd086e53939bef3e9a1a",
              "versionType": "git"
            },
            {
              "lessThan": "ed46f39c47eb5530a9c161481a2080d3a869cfaf",
              "status": "affected",
              "version": "ae98dbf43d755b4e111fcd086e53939bef3e9a1a",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "io_uring/net.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.94",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.36",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "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\nio_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries\n\nWhen a bundle recv retries inside io_recv_finish(), the merge logic OR\nthe saved cflags from the previous iteration with the cflags returned by\nthe new iteration:\n  cflags = req-\u003ecqe.flags | (cflags \u0026 CQE_F_MASK);\n\nBits listed in CQE_F_MASK are inherited from the new iteration, and all\nother bits (notably IORING_CQE_F_BUFFER and the buffer ID) come from the\nsaved cflags. Before this change CQE_F_MASK covered only\nIORING_CQE_F_SOCK_NONEMPTY and IORING_CQE_F_MORE.\n\nWhen using provided buffer rings (IOU_PBUF_RING_INC) with incremental\nmode, and bundle recv, io_kbuf_inc_commit() can leave the head ring\nentry partially consumed, __io_put_kbufs() then sets\nIORING_CQE_F_BUF_MORE on the returned cflags so userspace knows the\nbuffer ID will be reused for subsequent completions.\n\nBecause IORING_CQE_F_BUF_MORE was not in CQE_F_MASK, the merge above\nsilently dropped it whenever the final retry iteration partially\nconsumed the buffer, and the subsequent req-\u003ecqe.flags = cflags \u0026\n~CQE_F_MASK save would have left a stale IORING_CQE_F_BUF_MORE in the\ncarried-over cflags had one been present. Userspace would then\nwrongfully advance it ring head past an entry the kernel still uses.\n\nAdd IORING_CQE_F_BUF_MORE to CQE_F_MASK so it is both inherited from the\nnew iteration into the user-visible CQE and stripped from the saved\ncflags between iterations."
    }
  ],
  "id": "CVE-2026-53191",
  "lastModified": "2026-06-30T14:44:27.313",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-25T09:16:36.540",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0bbc9481f970b0b4ddb08cfa464db1cc93b74b56"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4973232a67e4137ab9399f504f7f2bdd847f96d2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ed46f39c47eb5530a9c161481a2080d3a869cfaf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f40570fda3f3a1f96aeaa4aef665ba274b2810b5"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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