Vulnerability-Lookup

GHSA-8CMF-4X36-QP8X

Vulnerability from github – Published: 2026-08-27 06:31 – Updated: 2026-08-27 06:31

Details

In the Linux kernel, the following vulnerability has been resolved:

s390/zcrypt: Improve CCA CPRB length and overflow checks

The xcrb_msg_to_type6cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Integer overflow after CEIL4 alignment: Signed int variables could overflow during 4-byte boundary alignment, causing undersized buffer allocations or incorrect bounds checking. 2. Missing minimum size validation: The CPRBX structure is copied from userspace without verifying sufficient buffer length. Undersized buffers cause uninitialized memory access when reading structure fields like cprbx.cprb_len and cprbx.domain. 3. Arithmetic overflow in sum calculations: Adding control block and data block sizes could overflow, bypassing size checks and enabling buffer overflows.

Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, validating minimum control block size before copying from userspace, and detecting sum calculation overflows.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80546"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-26T15:17:08Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/zcrypt: Improve CCA CPRB length and overflow checks\n\nThe xcrb_msg_to_type6cprb_msgx() function lacks proper input\nvalidation, creating security vulnerabilities:\n1. Integer overflow after CEIL4 alignment: Signed int variables could\n   overflow during 4-byte boundary alignment, causing undersized\n   buffer allocations or incorrect bounds checking.\n2. Missing minimum size validation: The CPRBX structure is copied from\n   userspace without verifying sufficient buffer length. Undersized\n   buffers cause uninitialized memory access when reading structure\n   fields like cprbx.cprb_len and cprbx.domain.\n3. Arithmetic overflow in sum calculations: Adding control block and\n   data block sizes could overflow, bypassing size checks and enabling\n   buffer overflows.\n\nFix by using size_t for length calculations, adding U32_MAX boundary\nchecks after alignment, validating minimum control block size before\ncopying from userspace, and detecting sum calculation overflows.",
  "id": "GHSA-8cmf-4x36-qp8x",
  "modified": "2026-08-27T06:31:31Z",
  "published": "2026-08-27T06:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80546"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/35ac6754ba6da45fd193f5ce3f665f7490b830d5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/50fe5133dcb46449daf2435fa705264364411129"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-80546 (GCVE-0-2026-80546)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 05:01

Title

s390/zcrypt: Improve CCA CPRB length and overflow checks

Summary

In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Improve CCA CPRB length and overflow checks The xcrb_msg_to_type6cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Integer overflow after CEIL4 alignment: Signed int variables could overflow during 4-byte boundary alignment, causing undersized buffer allocations or incorrect bounds checking. 2. Missing minimum size validation: The CPRBX structure is copied from userspace without verifying sufficient buffer length. Undersized buffers cause uninitialized memory access when reading structure fields like cprbx.cprb_len and cprbx.domain. 3. Arithmetic overflow in sum calculations: Adding control block and data block sizes could overflow, bypassing size checks and enabling buffer overflows. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, validating minimum control block size before copying from userspace, and detecting sum calculation overflows.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/50fe5133dcb46449d…
https://git.kernel.org/stable/c/35ac6754ba6da45fd…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 50fe5133dcb46449daf2435fa705264364411129 (git) Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 35ac6754ba6da45fd193f5ce3f665f7490b830d5 (git)
Linux	Linux	Affected: 7.1 Unaffected: 0 , < 7.1 (semver) Unaffected: 7.1.10 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/s390/crypto/zcrypt_msgtype6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "50fe5133dcb46449daf2435fa705264364411129",
              "status": "affected",
              "version": "e2c6d91eb8b1533753755f07803e47eceed263d0",
              "versionType": "git"
            },
            {
              "lessThan": "35ac6754ba6da45fd193f5ce3f665f7490b830d5",
              "status": "affected",
              "version": "e2c6d91eb8b1533753755f07803e47eceed263d0",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/s390/crypto/zcrypt_msgtype6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.10",
              "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": "7.1.10",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/zcrypt: Improve CCA CPRB length and overflow checks\n\nThe xcrb_msg_to_type6cprb_msgx() function lacks proper input\nvalidation, creating security vulnerabilities:\n1. Integer overflow after CEIL4 alignment: Signed int variables could\n   overflow during 4-byte boundary alignment, causing undersized\n   buffer allocations or incorrect bounds checking.\n2. Missing minimum size validation: The CPRBX structure is copied from\n   userspace without verifying sufficient buffer length. Undersized\n   buffers cause uninitialized memory access when reading structure\n   fields like cprbx.cprb_len and cprbx.domain.\n3. Arithmetic overflow in sum calculations: Adding control block and\n   data block sizes could overflow, bypassing size checks and enabling\n   buffer overflows.\n\nFix by using size_t for length calculations, adding U32_MAX boundary\nchecks after alignment, validating minimum control block size before\ncopying from userspace, and detecting sum calculation overflows."
        }
      ],
      "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 in xcrb_msg_to_type6cprb_msgx(), reached only from the ZSECSENDCPRB ioctl on the s390 zcrypt character device (zcrypt_unlocked_ioctl -\u003e zsecsendcprb_ioctl -\u003e _zcrypt_send_cprb -\u003e prep_cca_ap_msg); there is no network, adjacent-radio, or physical-bus entry point.\nAC:L - An attacker with a zcrypt fd fully controls the ica_xcRB length fields and CPRB buffers and can craft values that bypass flawed CEIL4/sum checks on every ioctl; no race, timing dependency, or uncontrolled memory layout is required.\nPR:L - Exploitation needs only local access to a zcrypt device node with ZSECSENDCPRB permitted via zcrypt_check_ioctl(); on IBM Z/LinuxONE admins routinely delegate such access to non-root crypto service accounts through custom zcdn nodes, not init-namespace root alone.\nUI:N - The attacker triggers the flaw directly by issuing ZSECSENDCPRB with a crafted ica_xcRB from their own process; no separate victim action such as mounting a filesystem or opening a file is required.\nS:U - Impact is heap corruption and kernel memory disclosure within the host kernel address space during AP message preparation; it does not cross a VM, IOMMU, or other changed security-authority boundary.\nC:H - Undersized request_control_blk_length copies fewer than sizeof(CPRBX) bytes yet the code reads cprbx.cprb_len and cprbx.domain from uninitialized kmalloc memory; integer-overflow bypasses can also yield out-of-bounds reads beyond the allocated ap_msg buffer.\nI:H - Signed-int CEIL4 alignment and sum overflows can make ap_msg-\u003elen smaller than copied data and place req_data before the kmalloc buffer, enabling z_copy_from_user() heap buffer overflows and attacker-influenced memory corruption suitable for control-flow hijack.\nA:H - Heap underflow/overflow and corrupted AP message buffers can immediately oops or panic the kernel; prep_cca_ap_msg runs before any crypto hardware is required, so the crash primitive is repeatable from ioctl alone."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T05:01:33.755Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/50fe5133dcb46449daf2435fa705264364411129"
        },
        {
          "url": "https://git.kernel.org/stable/c/35ac6754ba6da45fd193f5ce3f665f7490b830d5"
        }
      ],
      "title": "s390/zcrypt: Improve CCA CPRB length and overflow checks",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80546",
    "datePublished": "2026-08-26T14:37:17.550Z",
    "dateReserved": "2026-08-26T14:34:25.765Z",
    "dateUpdated": "2026-08-27T05:01:33.755Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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