CVE-2025-39963 (GCVE-0-2025-39963)
Vulnerability from cvelistv5
Published
2025-10-09 12:13
Modified
2026-08-05 12:06
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: fix incorrect io_kiocb reference in io_link_skb In io_link_skb function, there is a bug where prev_notif is incorrectly assigned using 'nd' instead of 'prev_nd'. This causes the context validation check to compare the current notification with itself instead of comparing it with the previous notification. Fix by using the correct prev_nd parameter when obtaining prev_notif.
References
Impacted products
Vendor Product Version
Linux Linux Version: 6fe4220912d19152a26ce19713ab232f4263018d
Version: 6fe4220912d19152a26ce19713ab232f4263018d
Version: 6fe4220912d19152a26ce19713ab232f4263018d
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/notif.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a89c34babc2e5834aa0905278f26f4dbe4b26b76",
              "status": "affected",
              "version": "6fe4220912d19152a26ce19713ab232f4263018d",
              "versionType": "git"
            },
            {
              "lessThan": "50a98ce1ea694f1ff8e87bc2f8f84096d1736f6a",
              "status": "affected",
              "version": "6fe4220912d19152a26ce19713ab232f4263018d",
              "versionType": "git"
            },
            {
              "lessThan": "2c139a47eff8de24e3350dadb4c9d5e3426db826",
              "status": "affected",
              "version": "6fe4220912d19152a26ce19713ab232f4263018d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "io_uring/notif.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.10"
            },
            {
              "lessThan": "6.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.49",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.49",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16.9",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: fix incorrect io_kiocb reference in io_link_skb\n\nIn io_link_skb function, there is a bug where prev_notif is incorrectly\nassigned using \u0027nd\u0027 instead of \u0027prev_nd\u0027. This causes the context\nvalidation check to compare the current notification with itself instead\nof comparing it with the previous notification.\n\nFix by using the correct prev_nd parameter when obtaining prev_notif."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerability is reached by submitting `IORING_OP_SEND_ZC` SQEs on a local io_uring instance, requiring local process execution; the attacker is the sender, so no remote peer can drive the path.\nAC:L - A single unprivileged process deterministically sets up the condition by creating two rings/threads and issuing consecutive SEND_ZC requests on one shared TCP socket whose peer is not draining, and it controls both sides of the subsequent cross-ring `compl_reqs` race.\nPR:L - No capability check exists anywhere on the path \u2014 `io_uring_setup()`, `io_send_zc_prep()`, and `tcp_sendmsg_locked()` are all available to any unprivileged user with default `kernel.io_uring_disabled=0`.\nUI:N - The attacker performs the entire sequence \u2014 ring creation, socket setup, and both zerocopy sends \u2014 inside their own process with no victim action required.\nS:U - The corruption is confined to the kernel\u0027s own io_uring request cache and completion lists; no virtualization, IOMMU, or other security-authority boundary is crossed.\nC:H - Corrupting another ring\u0027s `compl_reqs` list makes the same `io_kiocb` reachable from two live operations and posts CQEs into a foreign ring\u0027s completion queue, yielding a use-after-free that can be groomed into an arbitrary kernel-memory read.\nI:H - `io_free_batch_list()` runs `io_put_file()`, `io_put_task()`, and `io_req_add_to_cache()` on the corrupted list, giving double-free of `req_cachep` objects and `struct file` refcount underflow \u2014 classic stepping stones to arbitrary write and local privilege escalation.\nA:H - Even without successful grooming, cross-context chaining reliably produces list corruption, leaked never-completed requests that hang task/ring teardown, and on 6.18-era kernels a `WARN_ON_ONCE` that panics under `panic_on_warn`."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:06:32.066Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a89c34babc2e5834aa0905278f26f4dbe4b26b76"
        },
        {
          "url": "https://git.kernel.org/stable/c/50a98ce1ea694f1ff8e87bc2f8f84096d1736f6a"
        },
        {
          "url": "https://git.kernel.org/stable/c/2c139a47eff8de24e3350dadb4c9d5e3426db826"
        }
      ],
      "title": "io_uring: fix incorrect io_kiocb reference in io_link_skb",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39963",
    "datePublished": "2025-10-09T12:13:23.345Z",
    "dateReserved": "2025-04-16T07:20:57.149Z",
    "dateUpdated": "2026-08-05T12:06:32.066Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.