CVE-2026-63823 (GCVE-0-2026-63823)
Vulnerability from cvelistv5
Published
2026-07-19 12:02
Modified
2026-08-17 04:51
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: keys: Pin request_key_auth payload in instantiate paths A: request_key() B: KEYCTL_INSTANTIATE_IOV ================ ========================= create auth key store rka in auth key wait for helper get auth key load rka from auth key copy user payload sleep on #PF helper completed detach and free rka destroy auth key wake up use rka->target_key **USE-AFTER-FREE** Give request_key_auth payloads a refcount. Take a payload reference while authkey->sem stabilizes the payload and revocation state. Hold that reference across the instantiate and reject paths. Drop the auth key owning reference from revoke and destroy. [jarkko: Replaced the first two paragraphs of text with an actual concurrency scenario.]
References
Impacted products
Vendor Product Version
Linux Linux Version: b5f545c880a2a47947ba2118b2509644ab7a2969
Version: b5f545c880a2a47947ba2118b2509644ab7a2969
Version: b5f545c880a2a47947ba2118b2509644ab7a2969
Version: b5f545c880a2a47947ba2118b2509644ab7a2969
Version: b5f545c880a2a47947ba2118b2509644ab7a2969
Version: b5f545c880a2a47947ba2118b2509644ab7a2969
Version: b5f545c880a2a47947ba2118b2509644ab7a2969
Version: b5f545c880a2a47947ba2118b2509644ab7a2969
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/keys/request_key_auth-type.h",
            "security/keys/internal.h",
            "security/keys/keyctl.c",
            "security/keys/request_key_auth.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "b5f545c880a2a47947ba2118b2509644ab7a2969",
              "versionType": "git"
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            {
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/keys/request_key_auth-type.h",
            "security/keys/internal.h",
            "security/keys/keyctl.c",
            "security/keys/request_key_auth.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.16"
            },
            {
              "lessThan": "2.6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.260",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.260",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.211",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.177",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.144",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.95",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.38",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.3",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkeys: Pin request_key_auth payload in instantiate paths\n\nA: request_key()       B: KEYCTL_INSTANTIATE_IOV\n================       =========================\n\ncreate auth key\nstore rka in auth key\nwait for helper\n                       get auth key\n                       load rka from auth key\n                       copy user payload\n                       sleep on #PF\n\nhelper completed\ndetach and free rka\ndestroy auth key\n                       wake up\n                       use rka-\u003etarget_key\n                       **USE-AFTER-FREE**\n\nGive request_key_auth payloads a refcount.  Take a payload reference while\nauthkey-\u003esem stabilizes the payload and revocation state.  Hold that\nreference across the instantiate and reject paths.  Drop the auth key\nowning reference from revoke and destroy.\n\n[jarkko: Replaced the first two paragraphs of text with an actual\n concurrency scenario.]"
        }
      ],
      "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 bug is reached only through local `request_key()` and `keyctl()` syscalls (`KEYCTL_ASSUME_AUTHORITY`, `KEYCTL_INSTANTIATE`, `KEYCTL_INSTANTIATE_IOV`, `KEYCTL_REJECT`); there is no network, adjacent-radio, or physical-device entry path.\nAC:L - Exploitation is a race the attacker orchestrates by calling `request_key()` and concurrently driving `KEYCTL_INSTANTIATE_IOV` with a user buffer that page-faults during `copy_from_iter_full()`, while a second helper thread or completion path revokes/frees the auth payload.\nPR:L - Any unprivileged local user can invoke `request_key()` and the affected `keyctl` instantiate/reject operations in the spawned helper context; no real-root or non-userns capability is required.\nUI:N - Exploitation does not depend on a victim performing an action beyond the attacker\u2019s own syscall activity and helper process setup.\nS:U - Impact is kernel memory corruption and local privilege escalation within the same kernel security domain, not a VM-guest-to-host or IOMMU boundary escape.\nC:H - This is a heap use-after-free of `struct request_key_auth`; after free the code dereferences `rka-\u003etarget_key` and related fields, enabling attacker-controlled reuse and arbitrary kernel memory disclosure.\nI:H - The UAF corrupts trusted kernel pointers (`target_key`, `dest_keyring`) used in `key_instantiate_and_link()`, which can be turned into arbitrary kernel writes and local privilege escalation.\nA:H - Use-after-free of kernel heap objects can cause kernel oops/panic during post-fault dereferences, and is independently severe even before full exploitation."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:51:31.393Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d8274181b0f28d450b42489723a5ba81042158d7"
        },
        {
          "url": "https://git.kernel.org/stable/c/4982bfabce6b33b3c9eddb4fb900fe5568b7cf91"
        },
        {
          "url": "https://git.kernel.org/stable/c/708709c65a1832a99b0eef8ae46e343ddaca3d06"
        },
        {
          "url": "https://git.kernel.org/stable/c/35ab4db86774d82389e4b9559e26ab7f68d8e395"
        },
        {
          "url": "https://git.kernel.org/stable/c/f9b68632ac93cc742f2e411021c4dbfe452ea0c2"
        },
        {
          "url": "https://git.kernel.org/stable/c/7216ce8cb12fee44e309503955bb83806b106129"
        },
        {
          "url": "https://git.kernel.org/stable/c/83c0a1cb296d955d5f4d1f0bd8a769ba8ed8c29f"
        },
        {
          "url": "https://git.kernel.org/stable/c/fd15b457a86939c38aa12116adabd8ff686c5e51"
        }
      ],
      "title": "keys: Pin request_key_auth payload in instantiate paths",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63823",
    "datePublished": "2026-07-19T12:02:19.847Z",
    "dateReserved": "2026-07-19T07:54:57.014Z",
    "dateUpdated": "2026-08-17T04:51:31.393Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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