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GHSA-5H39-F843-4G5V

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 EP11 CPRB length and overflow checks

The xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Missing minimum size validation: The ep11_cprb structure and subsequent payload fields (pld_tag, pld_lenfmt) are copied from userspace without verifying sufficient buffer length. 2. Arithmetic overflow in length calculations: CEIL4 alignment could overflow, bypassing size checks and enabling buffer overflows. 3. The payload is asn1 encoded but the function just uses a simple c struct overlay to access some fields of the payload.

Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, and validating minimum request size and minimum reply size before copying from userspace. Do a very simple asn1 parsing of the payload up to the function value field.

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-2026-80545"
  ],
  "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 EP11 CPRB length and overflow checks\n\nThe xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input\nvalidation, creating security vulnerabilities:\n1. Missing minimum size validation: The ep11_cprb structure and\n   subsequent payload fields (pld_tag, pld_lenfmt) are copied from\n   userspace without verifying sufficient buffer length.\n2. Arithmetic overflow in length calculations: CEIL4 alignment could\n   overflow, bypassing size checks and enabling buffer overflows.\n3. The payload is asn1 encoded but the function just uses a simple c\n   struct overlay to access some fields of the payload.\n\nFix by using size_t for length calculations, adding U32_MAX boundary\nchecks after alignment, and validating minimum request size and\nminimum reply size before copying from userspace. Do a very simple\nasn1 parsing of the payload up to the function value field.",
  "id": "GHSA-5h39-f843-4g5v",
  "modified": "2026-08-27T06:31:31Z",
  "published": "2026-08-27T06:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80545"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/17ac0bc866fc624cd05f022dcd8b730c0af11bb1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2976b9d2e716c7e5487ca7c29a7bd076cf9adf08"
    }
  ],
  "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-2026-80545 (GCVE-0-2026-80545)

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

Title

s390/zcrypt: Improve EP11 CPRB length and overflow checks

Summary

In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Improve EP11 CPRB length and overflow checks The xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Missing minimum size validation: The ep11_cprb structure and subsequent payload fields (pld_tag, pld_lenfmt) are copied from userspace without verifying sufficient buffer length. 2. Arithmetic overflow in length calculations: CEIL4 alignment could overflow, bypassing size checks and enabling buffer overflows. 3. The payload is asn1 encoded but the function just uses a simple c struct overlay to access some fields of the payload. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, and validating minimum request size and minimum reply size before copying from userspace. Do a very simple asn1 parsing of the payload up to the function value field.

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/2976b9d2e716c7e54…
https://git.kernel.org/stable/c/17ac0bc866fc624cd…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 2976b9d2e716c7e5487ca7c29a7bd076cf9adf08 (git) Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 17ac0bc866fc624cd05f022dcd8b730c0af11bb1 (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"
          ],
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          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2976b9d2e716c7e5487ca7c29a7bd076cf9adf08",
              "status": "affected",
              "version": "e2c6d91eb8b1533753755f07803e47eceed263d0",
              "versionType": "git"
            },
            {
              "lessThan": "17ac0bc866fc624cd05f022dcd8b730c0af11bb1",
              "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"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                }
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              "negate": false,
              "operator": "OR"
            }
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        }
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/zcrypt: Improve EP11 CPRB length and overflow checks\n\nThe xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input\nvalidation, creating security vulnerabilities:\n1. Missing minimum size validation: The ep11_cprb structure and\n   subsequent payload fields (pld_tag, pld_lenfmt) are copied from\n   userspace without verifying sufficient buffer length.\n2. Arithmetic overflow in length calculations: CEIL4 alignment could\n   overflow, bypassing size checks and enabling buffer overflows.\n3. The payload is asn1 encoded but the function just uses a simple c\n   struct overlay to access some fields of the payload.\n\nFix by using size_t for length calculations, adding U32_MAX boundary\nchecks after alignment, and validating minimum request size and\nminimum reply size before copying from userspace. Do a very simple\nasn1 parsing of the payload up to the function value field."
        }
      ],
      "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"
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            {
              "lang": "en",
              "value": "AV:L - The flaw is reached only via local ioctl(ZSENDEP11CPRB) on /dev/z90crypt or administrator-created zcdn device nodes on IBM Z systems with EP11 crypto hardware; there is no network, Bluetooth, or USB packet path to this code.\nAC:L - The attacker fully controls ep11_urb req_len, req, and resp_len in the ioctl argument; near-SIZE_MAX lengths can wrap CEIL4 sum checks to bypass bufsize validation and trigger deterministic heap corruption without races or external timing dependencies.\nPR:L - Exploitation requires opening a zcrypt device and passing zcrypt_check_ioctl, access routinely delegated to non-root application/service accounts via zcdn nodes on shared IBM Z cloud, LPAR, and container deployments that grant EP11 CPRB ioctl permissions.\nUI:N - Triggering is self-contained by submitting a crafted EP11 request block through ioctl; no victim interaction, file opening by another user, or administrative action beyond having zcrypt device access is required.\nS:U - Impact is kernel heap corruption and privilege escalation within the same Linux security authority on the s390 host; it does not cross VM, IOMMU, or container sandbox boundaries to affect a separate security domain.\nC:H - Undersized copies leave uninitialized kmalloc data readable via struct overlays on pld_lenfmt and payload_hdr, while integer-overflowed req_len values enable copy_from_user far beyond the ap_msg buffer, providing arbitrary kernel memory disclosure primitives.\nI:H - Missing minimum-size and U32_MAX boundary checks let attacker-controlled lengths bypass ap_msg-\u003elen validation and corrupt adjacent kmalloc objects in the crypto message buffer, enabling heap control primitives and potential arbitrary kernel code execution.\nA:H - Heap buffer overflow and out-of-bounds parsing of EP11 CPRB payloads can cause kernel oops, panic, or denial of crypto services on mission-critical IBM Z systems; memory corruption alone threatens host availability even before full exploitation."
            }
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        }
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        "dateUpdated": "2026-08-27T05:01:32.688Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/2976b9d2e716c7e5487ca7c29a7bd076cf9adf08"
        },
        {
          "url": "https://git.kernel.org/stable/c/17ac0bc866fc624cd05f022dcd8b730c0af11bb1"
        }
      ],
      "title": "s390/zcrypt: Improve EP11 CPRB length and overflow checks",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80545",
    "datePublished": "2026-08-26T14:37:16.956Z",
    "dateReserved": "2026-08-26T14:34:25.765Z",
    "dateUpdated": "2026-08-27T05:01:32.688Z",
    "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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GHSA-5H39-F843-4G5V

CVE-2026-80545 (GCVE-0-2026-80545)

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Sightings

Nomenclature