CVE-2026-64558 (GCVE-0-2026-64558)

Vulnerability from cvelistv5 – Published: 2026-07-29 16:31 – Updated: 2026-08-05 12:43
VLAI
Title
s390/pkey: Check length in pkey_pckmo handler implementation
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.
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: 8fcc231ce3bea12b78bb94b280cdc03cff342435 , < 02028a24e26d85262ab9c8fc4344e1f3503007fc (git)
Affected: 8fcc231ce3bea12b78bb94b280cdc03cff342435 , < 433e5e70cdc1edf382d28d08a885b22e2b98b7da (git)
Affected: 8fcc231ce3bea12b78bb94b280cdc03cff342435 , < 614aa0491c7a190556c2345dddee0b6f5ed90989 (git)
Affected: 8fcc231ce3bea12b78bb94b280cdc03cff342435 , < 1ac287e2af9a9112fe271427ef45eceb26bce8b4 (git)
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Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/s390/crypto/pkey_pckmo.c"
          ],
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              "versionType": "git"
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              "versionType": "semver"
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              "versionType": "semver"
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              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              ],
              "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": "2026-08-05T12:43:03.921Z",
        "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"
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  "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": "2026-08-05T12:43:03.921Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-64558",
      "date": "2026-08-09",
      "epss": "0.0012",
      "percentile": "0.02112"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64558\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-29T17:16:53.410\",\"lastModified\":\"2026-07-30T06:25:59.600\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/s390/crypto/pkey_pckmo.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"8fcc231ce3bea12b78bb94b280cdc03cff342435\",\"lessThan\":\"02028a24e26d85262ab9c8fc4344e1f3503007fc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"8fcc231ce3bea12b78bb94b280cdc03cff342435\",\"lessThan\":\"433e5e70cdc1edf382d28d08a885b22e2b98b7da\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"8fcc231ce3bea12b78bb94b280cdc03cff342435\",\"lessThan\":\"614aa0491c7a190556c2345dddee0b6f5ed90989\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"8fcc231ce3bea12b78bb94b280cdc03cff342435\",\"lessThan\":\"1ac287e2af9a9112fe271427ef45eceb26bce8b4\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/s390/crypto/pkey_pckmo.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/02028a24e26d85262ab9c8fc4344e1f3503007fc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1ac287e2af9a9112fe271427ef45eceb26bce8b4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/433e5e70cdc1edf382d28d08a885b22e2b98b7da\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/614aa0491c7a190556c2345dddee0b6f5ed90989\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-07-30T07:45:02+00:00",
      "cve": "CVE-2026-64558",
      "id": "CVE-2026-64558",
      "initial_release_date": "2026-07-29T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: s390/pkey: Check length in pkey_pckmo handler implementation",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64558.json",
      "version": "3"
    }
  }
}



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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

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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.