Vulnerability-Lookup

PYSEC-2026-3625

Vulnerability from pysec - Published: 2026-06-30 22:16 - Updated: 2026-08-07 09:08

Details

MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.1, there is an Out-of-bounds read/crash on Unpacker reuse after a caught error, potentially leading to a DoS attack. If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. This issue has been fixed in version 1.2.1.

Severity

7.5 (High)


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

Impacted products

Name	purl
msgpack	pkg:pypi/msgpack

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {},
      "package": {
        "ecosystem": "PyPI",
        "name": "msgpack",
        "purl": "pkg:pypi/msgpack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.5.0",
        "0.5.1",
        "0.5.2",
        "0.5.3",
        "0.5.4",
        "0.5.5",
        "0.5.6",
        "0.6.0",
        "0.6.1",
        "0.6.2",
        "1.0.0",
        "1.0.0rc1",
        "1.0.1",
        "1.0.2",
        "1.0.3",
        "1.0.3rc1",
        "1.0.4",
        "1.0.4rc1",
        "1.0.5",
        "1.0.5rc1",
        "1.0.6",
        "1.0.6rc1",
        "1.0.7",
        "1.0.8",
        "1.1.0",
        "1.1.0rc1",
        "1.1.0rc2",
        "1.1.1",
        "1.1.1rc1",
        "1.1.2",
        "1.2.0",
        "1.2.0rc1"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-57585",
    "GHSA-6v7p-g79w-8964"
  ],
  "details": "MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.1, there is an Out-of-bounds read/crash on Unpacker reuse after a caught error, potentially leading to a DoS attack.  If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. This issue has been fixed in version 1.2.1.",
  "id": "PYSEC-2026-3625",
  "modified": "2026-08-07T09:08:06.271171Z",
  "published": "2026-06-30T22:16:57.837Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964"
    },
    {
      "type": "FIX",
      "url": "https://github.com/msgpack/msgpack-python/commit/2c56ddb5d0025ed481d962c0f5d62d19dec7476d"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-57585 (GCVE-0-2026-57585)

Vulnerability from cvelistv5 – Published: 2026-06-30 21:36 – Updated: 2026-07-01 14:54

Title

MessagePack: Out-of-bounds read/crash on Unpacker reuse after caught error

Summary

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-01 14:54 UTC

CWE

CWE-416 - Use After Free

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/msgpack/msgpack-python/securit…	x_refsource_CONFIRM
https://github.com/msgpack/msgpack-python/commit/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
msgpack	msgpack-python	Affected: < 1.2.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-57585",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-01T14:54:21.105642Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-01T14:54:36.191Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "msgpack-python",
          "vendor": "msgpack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.2.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.1, there is an Out-of-bounds read/crash on Unpacker reuse after a caught error, potentially leading to a DoS attack.  If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. This issue has been fixed in version 1.2.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-416",
              "description": "CWE-416: Use After Free",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-30T21:36:23.418Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964"
        },
        {
          "name": "https://github.com/msgpack/msgpack-python/commit/2c56ddb5d0025ed481d962c0f5d62d19dec7476d",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/msgpack/msgpack-python/commit/2c56ddb5d0025ed481d962c0f5d62d19dec7476d"
        }
      ],
      "source": {
        "advisory": "GHSA-6v7p-g79w-8964",
        "discovery": "UNKNOWN"
      },
      "title": "MessagePack: Out-of-bounds read/crash on Unpacker reuse after caught error"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-57585",
    "datePublished": "2026-06-30T21:36:23.418Z",
    "dateReserved": "2026-06-24T18:49:56.209Z",
    "dateUpdated": "2026-07-01T14:54:36.191Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-6V7P-G79W-8964

Vulnerability from github – Published: 2026-06-19 21:42 – Updated: 2026-06-19 21:42

Summary

MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error

Details

Impact

If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV.

If the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack.

Patches

v1.2.1

Workarounds

Users should create a new Unpacker instead of reusing the same Unpacker after an error occurs.

Applying the above patch can prevent SEGV, but reusing the Streaming Unpacker after it has encountered an error will not yield correct data. If an error occurs during Streaming Unpacking, the Stream and Streaming Unpacker should be discarded.

Therefore, this is not just a workaround but the correct solution. The above patch only prevents crashes from incorrect usage.

Severity

7.5 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.2.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "msgpack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T21:42:55Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\n\nIf the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV.\n\nIf the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack.\n\n### Patches\n\nv1.2.1\n\n### Workarounds\n\nUsers should create a new Unpacker instead of reusing the same Unpacker after an error occurs.\n\nApplying the above patch can prevent SEGV, but reusing the Streaming Unpacker after it has encountered an error will not yield correct data. If an error occurs during Streaming Unpacking, the Stream and Streaming Unpacker should be discarded.\n\nTherefore, this is not just a workaround but the correct solution. The above patch only prevents crashes from incorrect usage.",
  "id": "GHSA-6v7p-g79w-8964",
  "modified": "2026-06-19T21:42:55Z",
  "published": "2026-06-19T21:42:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964"
    },
    {
      "type": "WEB",
      "url": "https://github.com/msgpack/msgpack-python/commit/2c56ddb5d0025ed481d962c0f5d62d19dec7476d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/msgpack/msgpack-python"
    },
    {
      "type": "WEB",
      "url": "https://github.com/msgpack/msgpack-python/releases/tag/v1.2.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error"
}

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.

Action not permitted

PYSEC-2026-3625

CVE-2026-57585 (GCVE-0-2026-57585)

GHSA-6V7P-G79W-8964

Impact

Patches

Workarounds

Tags

Sightings

Nomenclature