CVE-2025-68317 (GCVE-0-2025-68317)

Vulnerability from cvelistv5 – Published: 2025-12-16 15:39 – Updated: 2026-08-05 12:10
VLAI
Title
io_uring/zctx: check chained notif contexts
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring/zctx: check chained notif contexts Send zc only links ubuf_info for requests coming from the same context. There are some ambiguous syz reports, so let's check the assumption on notification completion.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 6fe4220912d19152a26ce19713ab232f4263018d , < aaafd17d3f4be2c15539359a5b4bfa00237f687f (git)
Affected: 6fe4220912d19152a26ce19713ab232f4263018d , < d664a3ce3a604231a0b144c152a3755d03b18b60 (git)
Affected: 6fe4220912d19152a26ce19713ab232f4263018d , < ab3ea6eac5f45669b091309f592c4ea324003053 (git)
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Linux Linux Affected: 6.10
Unaffected: 0 , < 6.10 (semver)
Unaffected: 6.12.58 , ≤ 6.12.* (semver)
Unaffected: 6.17.8 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
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{
  "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": [
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              "status": "affected",
              "version": "6fe4220912d19152a26ce19713ab232f4263018d",
              "versionType": "git"
            },
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          "product": "Linux",
          "programFiles": [
            "io_uring/notif.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "6.10"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.17.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.58",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
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                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "6.18",
                  "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/zctx: check chained notif contexts\n\nSend zc only links ubuf_info for requests coming from the same context.\nThere are some ambiguous syz reports, so let\u0027s check the assumption on\nnotification completion."
        }
      ],
      "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 - A local process reaches the flaw by submitting IORING_OP_SEND_ZC or IORING_OP_SENDMSG_ZC requests through io_uring. Remote packets alone cannot construct the required cross-ring notification chain.\nAC:L - The attacker can deterministically reuse a TCP skb with small sends and MSG_MORE across two attacker-created rings. Any completion-list race is attacker-controlled through concurrent submissions and ACK or socket timing.\nPR:L - Normal io_uring setup, TCP socket creation, and zero-copy sends require no capabilities when io_uring is enabled. An ordinary unprivileged account with a small buffer within RLIMIT_MEMLOCK can reach the flaw without user namespaces.\nUI:N - The attacker creates the rings, submits both sends, and causes skb completion without any victim action.\nS:U - The corruption affects the host kernel and represents a standard local privilege-escalation boundary rather than a VM, IOMMU, or other security-scope escape.\nC:H - Wrong-context completion modifies a foreign ring\u2019s completion list without its mutex; racing a flush can corrupt its request free list and reallocate a still-linked notification, producing UAF and type confusion capable of kernel-memory disclosure. [NVD assigns C:H to the same root-cause defect](https://nvd.nist.gov/vuln/detail/CVE-2025-39963).\nI:H - The corrupted free list permits an active io_kiocb to be reused and subsequently interpreted as notification data, enabling kernel heap corruption and potentially arbitrary writes or control-flow hijacking.\nA:H - The wrong-lock completion has been observed by [syzkaller](https://syzkaller.appspot.com/bug?id=423c19d7bb9000c4ddc 1c63f9faface466fb6c35); without the diagnostic stopping execution, the resulting list corruption can cause an oops, panic, hang, or repeatable resource leak."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:10:50.931Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/aaafd17d3f4be2c15539359a5b4bfa00237f687f"
        },
        {
          "url": "https://git.kernel.org/stable/c/d664a3ce3a604231a0b144c152a3755d03b18b60"
        },
        {
          "url": "https://git.kernel.org/stable/c/ab3ea6eac5f45669b091309f592c4ea324003053"
        }
      ],
      "title": "io_uring/zctx: check chained notif contexts",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68317",
    "datePublished": "2025-12-16T15:39:47.159Z",
    "dateReserved": "2025-12-16T14:48:05.295Z",
    "dateUpdated": "2026-08-05T12:10:50.931Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-68317",
      "date": "2026-08-07",
      "epss": "0.00126",
      "percentile": "0.02654"
    },
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    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-07-30T10:07:19+00:00",
      "cve": "CVE-2025-68317",
      "id": "CVE-2025-68317",
      "initial_release_date": "2025-12-16T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: Denial of Service via improper handling of io_uring notification contexts",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-68317.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-19T17:45:09Z",
      "cve": "CVE-2025-68317",
      "id": "CVE-2025-68317",
      "initial_release_date": "2025-12-17T00:23:45Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "394",
      "product_status:known_not_affected": "429",
      "product_status:recommended": "172",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-68317",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-68317.json",
      "version": "25"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.