Vulnerability-Lookup

OESA-2026-3221 (CVE-2026-54522)

Vulnerability from osv_openeuler – Published: 2026-08-01 11:12 – Updated: 2026-08-06 11:12 – Source website

Summary

rubygem-msgpack security update

Details

MessagePack is a binary-based efficient object serialization library. It enables to exchange structured objects between many languages like JSON. But unlike JSON, it is very fast and small.

Security Fix(es):

Affected versions of this package are vulnerable to Use After Free in the clear function. An attacker can access or manipulate memory contents from another buffer by triggering the reuse of a memory page after it has been returned to the shared pool, leading to unintended disclosure or modification of data.(CVE-2026-54522)

Severity

7.3 (High)


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

References

URL

Type

	https://www.openeuler.org/zh/security/security-bu…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2026-54522	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "aarch64": [
          "rubygem-msgpack-1.8.3-1.oe2403sp3.aarch64.rpm",
          "rubygem-msgpack-debuginfo-1.8.3-1.oe2403sp3.aarch64.rpm",
          "rubygem-msgpack-debugsource-1.8.3-1.oe2403sp3.aarch64.rpm"
        ],
        "noarch": [
          "rubygem-msgpack-help-1.8.3-1.oe2403sp3.noarch.rpm"
        ],
        "src": [
          "rubygem-msgpack-1.8.3-1.oe2403sp3.src.rpm"
        ],
        "x86_64": [
          "rubygem-msgpack-1.8.3-1.oe2403sp3.x86_64.rpm",
          "rubygem-msgpack-debuginfo-1.8.3-1.oe2403sp3.x86_64.rpm",
          "rubygem-msgpack-debugsource-1.8.3-1.oe2403sp3.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP3",
        "name": "rubygem-msgpack",
        "purl": "pkg:rpm/openEuler/rubygem-msgpack\u0026distro=openEuler-24.03-LTS-SP3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.8.3-1.oe2403sp3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "High"
  },
  "details": "MessagePack is a binary-based efficient object serialization library. It enables to exchange structured objects between many languages like JSON. But unlike JSON, it is very fast and small.\r\n\r\nSecurity Fix(es):\n\nAffected versions of this package are vulnerable to Use After Free in the `clear` function. An attacker can access or manipulate memory contents from another buffer by triggering the reuse of a memory page after it has been returned to the shared pool, leading to unintended disclosure or modification of data.(CVE-2026-54522)",
  "id": "OESA-2026-3221",
  "modified": "2026-08-06T11:12:05Z",
  "published": "2026-08-01T11:12:05Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-3221"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54522"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "rubygem-msgpack security update",
  "upstream": [
    "CVE-2026-54522"
  ]
}

CVE-2026-54522 (GCVE-0-2026-54522)

Vulnerability from cvelistv5 – Published: 2026-07-30 16:33 – Updated: 2026-07-30 17:39

Title

MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure

Summary

MessagePack for Ruby is an implementation of the MessagePack binary serialization format. Prior to 1.8.2, MessagePack::Buffer#clear in ext/msgpack/buffer.c leaves rmem_last, rmem_end, and rmem_owner stale after _msgpack_buffer_shift_chunk returns an rmem page to the shared pool, allowing a subsequent Buffer#write and a second MessagePack::Buffer to alias the page and disclose or corrupt cross-buffer data. This issue is fixed in version 1.8.2.

Severity

2.1 (Low)


                        
                          CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-30 17:38 UTC

CWE

CWE-416 - Use After Free

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/msgpack/msgpack-ruby/security/…	x_refsource_CONFIRM
https://github.com/msgpack/msgpack-ruby/commit/56…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
msgpack	msgpack-ruby	Affected: < 1.8.2

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-54522",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-30T17:38:58.315032Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-30T17:39:15.020Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "msgpack-ruby",
          "vendor": "msgpack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "MessagePack for Ruby is an implementation of the MessagePack binary serialization format. Prior to 1.8.2, MessagePack::Buffer#clear in ext/msgpack/buffer.c leaves rmem_last, rmem_end, and rmem_owner stale after _msgpack_buffer_shift_chunk returns an rmem page to the shared pool, allowing a subsequent Buffer#write and a second MessagePack::Buffer to alias the page and disclose or corrupt cross-buffer data. This issue is fixed in version 1.8.2."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "LOCAL",
            "baseScore": 2.1,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-416",
              "description": "CWE-416: Use After Free",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-30T16:33:06.080Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938"
        },
        {
          "name": "https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90"
        }
      ],
      "source": {
        "advisory": "GHSA-4mrv-5p47-p938",
        "discovery": "UNKNOWN"
      },
      "title": "MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-54522",
    "datePublished": "2026-07-30T16:33:06.080Z",
    "dateReserved": "2026-06-15T18:40:01.651Z",
    "dateUpdated": "2026-07-30T17:39:15.020Z",
    "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.

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

OESA-2026-3221 (CVE-2026-54522)

CVE-2026-54522 (GCVE-0-2026-54522)

Tags

Sightings

Nomenclature

Related by attack behaviour