CVE-2026-64558 (GCVE-0-2026-64558)
Vulnerability from cvelistv5
Published
2026-07-29 16:31
Modified
2026-08-17 04:57
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: s390/pkey: Check length in pkey_pckmo handler implementation Explicitly check the length of the target buffer in the pkey_pckmo implementation of the key_to_protkey() handler function. The handler function fails, if the generated output data exceeds the length of the provided target buffer.
References
Impacted products
Vendor Product Version
Linux Linux Version: 8fcc231ce3bea12b78bb94b280cdc03cff342435
Version: 8fcc231ce3bea12b78bb94b280cdc03cff342435
Version: 8fcc231ce3bea12b78bb94b280cdc03cff342435
Version: 8fcc231ce3bea12b78bb94b280cdc03cff342435
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/s390/crypto/pkey_pckmo.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "02028a24e26d85262ab9c8fc4344e1f3503007fc",
              "status": "affected",
              "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435",
              "versionType": "git"
            },
            {
              "lessThan": "433e5e70cdc1edf382d28d08a885b22e2b98b7da",
              "status": "affected",
              "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435",
              "versionType": "git"
            },
            {
              "lessThan": "614aa0491c7a190556c2345dddee0b6f5ed90989",
              "status": "affected",
              "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435",
              "versionType": "git"
            },
            {
              "lessThan": "1ac287e2af9a9112fe271427ef45eceb26bce8b4",
              "status": "affected",
              "version": "8fcc231ce3bea12b78bb94b280cdc03cff342435",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/s390/crypto/pkey_pckmo.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": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "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": "6.12.97",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/pkey: Check length in pkey_pckmo handler implementation\n\nExplicitly check the length of the target buffer in the pkey_pckmo\nimplementation of the key_to_protkey() handler function. The handler\nfunction fails, if the generated output data exceeds the length of the\nprovided target buffer."
        }
      ],
      "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 vulnerable path is entered through the PKEY_KBLOB2PROTK/PKEY_KBLOB2PROTK2 ioctls on the /dev/pkey character device, or via an AF_ALG setkey on the paes skciphers. Both require local system access; no network input reaches this code.\nAC:L - A single ioctl with a hand-crafted 176-byte protected-key token (type 0x00, version TOKVER_PROTECTED_KEY, keytype PKEY_KEYTYPE_HMAC_1024, len 160) deterministically triggers the 96-byte overflow; there is no race, no memory-layout dependency, and no hardware or wrapping-key prerequisite since the non-AES branch skips pckmo_verify_protkey().\nPR:L - /dev/pkey is registered as a miscdevice with .mode = 0666 and pkey_unlocked_ioctl() contains no capability or permission check, so any unprivileged local user can reach the bug; the paes/AF_ALG setkey path likewise requires no privileges.\nUI:N - The attacker triggers the overflow entirely on their own via a single ioctl or socket option call; no victim action, mount, or file open is involved.\nS:U - The corruption is confined to the kernel\u0027s own stack within the same security authority; exploitation yields kernel privilege escalation rather than crossing a VM, IOMMU, or sandbox boundary.\nC:H - The attacker gains a fully controlled 96-byte out-of-bounds stack write that can clobber adjacent locals, saved pointers and return addresses, which is readily leveraged into arbitrary kernel memory disclosure; the copy also leaves *protkeylen inflated to 160 while the buffer is 64 bytes, feeding an oversized length back to callers.\nI:H - This is an out-of-bounds write of 96 attacker-chosen bytes past the end of a kernel stack object (the last member of struct pkey_kblob2pkey), overwriting saved registers and the return address \u2014 a classic control-flow hijack / local privilege escalation primitive.\nA:H - Smashing the kernel stack past the canary reliably produces a stack-protector panic or an oops on return, and any unprivileged user can repeat it at will to crash the machine."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:57:36.699Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/02028a24e26d85262ab9c8fc4344e1f3503007fc"
        },
        {
          "url": "https://git.kernel.org/stable/c/433e5e70cdc1edf382d28d08a885b22e2b98b7da"
        },
        {
          "url": "https://git.kernel.org/stable/c/614aa0491c7a190556c2345dddee0b6f5ed90989"
        },
        {
          "url": "https://git.kernel.org/stable/c/1ac287e2af9a9112fe271427ef45eceb26bce8b4"
        }
      ],
      "title": "s390/pkey: Check length in pkey_pckmo handler implementation",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64558",
    "datePublished": "2026-07-29T16:31:21.591Z",
    "dateReserved": "2026-07-19T15:36:31.796Z",
    "dateUpdated": "2026-08-17T04:57:36.699Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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