Vulnerability-Lookup

FKIE_CVE-2026-3276

Vulnerability from fkie_nvd - Published: 2026-06-03 16:16 - Updated: 2026-08-13 01:16

Severity

6.3 (Medium) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Summary

unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating Canonical Combining Class values. This affects all normalization forms.

References

	URL	Tags
	cna@python.org	https://github.com/python/cpython/commit/6b505d1f41f8f3ea0fe5a4786d3a8fff1875cfc0
	cna@python.org	https://github.com/python/cpython/commit/90748760d38ca3ac5fc6788a69becab905c95598
	cna@python.org	https://github.com/python/cpython/commit/991224b1e8311c85f198f6dd8208bf8cff7fc26f
	cna@python.org	https://github.com/python/cpython/commit/ba785b88add96acbf403d65cb157fb2743a33a32
	cna@python.org	https://github.com/python/cpython/commit/c5512bd7c1dc28055660565275012766941d3066
	cna@python.org	https://github.com/python/cpython/commit/d3ab945af25b28dfe13ac6cb40c124a01b33ce1f
	cna@python.org	https://github.com/python/cpython/commit/db744c0776c1d5dd11aaa70eff2a6993c408bacc
	cna@python.org	https://github.com/python/cpython/commit/e322a1857084d521f79f45181b776f62e6acfc2c
	cna@python.org	https://github.com/python/cpython/issues/149079
	cna@python.org	https://github.com/python/cpython/pull/149080
	cna@python.org	https://mail.python.org/archives/list/security-announce@python.org/thread/PP5HB4K7727OBBM76KA2ILID76K3OZGZ/
	af854a3a-2127-422b-91ae-364da2661108	http://www.openwall.com/lists/oss-security/2026/06/03/15

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "CPython",
          "repo": "https://github.com/python/cpython",
          "vendor": "Python Software Foundation",
          "versions": [
            {
              "lessThan": "3.10.21",
              "status": "affected",
              "version": "0",
              "versionType": "python"
            },
            {
              "lessThan": "3.11.16",
              "status": "affected",
              "version": "3.11.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.12.14",
              "status": "affected",
              "version": "3.12.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.13.14",
              "status": "affected",
              "version": "3.13.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.14.6",
              "status": "affected",
              "version": "3.14.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.15.0b2",
              "status": "affected",
              "version": "3.15.0a1",
              "versionType": "python"
            }
          ]
        }
      ],
      "source": "cna@python.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "unicodedata.normalize() can take excessive CPU time when processing\nspecially crafted Unicode input containing long runs of combining characters\nwith alternating Canonical Combining Class values.\nThis affects all normalization forms."
    },
    {
      "lang": "es",
      "value": "unicodedata.normalize() puede consumir un tiempo excesivo de CPU al procesar entradas Unicode especialmente dise\u00f1adas que contienen largas secuencias de caracteres combinatorios con valores de Clase de Combinaci\u00f3n Can\u00f3nica alternos. Esto afecta a todas las formas de normalizaci\u00f3n."
    }
  ],
  "id": "CVE-2026-3276",
  "lastModified": "2026-08-13T01:16:52.847",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "LOW",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "cna@python.org",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-3276",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-06-03T17:27:09.393265Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-06-03T16:16:29.253",
  "references": [
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/6b505d1f41f8f3ea0fe5a4786d3a8fff1875cfc0"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/90748760d38ca3ac5fc6788a69becab905c95598"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/991224b1e8311c85f198f6dd8208bf8cff7fc26f"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/ba785b88add96acbf403d65cb157fb2743a33a32"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/c5512bd7c1dc28055660565275012766941d3066"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/d3ab945af25b28dfe13ac6cb40c124a01b33ce1f"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/db744c0776c1d5dd11aaa70eff2a6993c408bacc"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/e322a1857084d521f79f45181b776f62e6acfc2c"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/issues/149079"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/pull/149080"
    },
    {
      "source": "cna@python.org",
      "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/PP5HB4K7727OBBM76KA2ILID76K3OZGZ/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "http://www.openwall.com/lists/oss-security/2026/06/03/15"
    }
  ],
  "sourceIdentifier": "cna@python.org",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-407"
        }
      ],
      "source": "cna@python.org",
      "type": "Secondary"
    }
  ]
}

CVE-2026-3276 (GCVE-0-2026-3276)

Vulnerability from cvelistv5 – Published: 2026-06-03 14:29 – Updated: 2026-08-13 00:28

Title

Potential DoS via quadratic complexity in unicodedata.normalize()

Summary

Severity

6.3 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-03 17:27 UTC

CWE

CWE-407

Assigner

PSF mitre root

References

12 references

URL	Tags
https://mail.python.org/archives/list/security-an…	vendor-advisory
https://github.com/python/cpython/pull/149080	patch
https://github.com/python/cpython/issues/149079	issue-tracking
https://github.com/python/cpython/commit/6b505d1f…	patch
https://github.com/python/cpython/commit/991224b1…	patch
https://github.com/python/cpython/commit/ba785b88…	patch
https://github.com/python/cpython/commit/c5512bd7…	patch
https://github.com/python/cpython/commit/90748760…	patch
https://github.com/python/cpython/commit/d3ab945a…	patch
https://github.com/python/cpython/commit/db744c07…	patch
https://github.com/python/cpython/commit/e322a185…	patch
http://www.openwall.com/lists/oss-security/2026/0…

Impacted products

1 product

Vendor	Product	Version
Python Software Foundation	CPython	Affected: 0 , < 3.10.21 (python) Affected: 3.11.0 , < 3.11.16 (python) Affected: 3.12.0 , < 3.12.14 (python) Affected: 3.13.0 , < 3.13.14 (python) Affected: 3.14.0 , < 3.14.6 (python) Affected: 3.15.0a1 , < 3.15.0b2 (python)

Credits

Seokchan Yoon (https://github.com/ch4n3-yoon) Tim Peters (https://github.com/tim-one) Bénédikt Tran (https://github.com/picnixz) Serhiy Storchaka (https://github.com/serhiy-storchaka) Stan Ulbrych (https://github.com/StanFromIreland) Seth Larson (https://github.com/sethmlarson) Petr Viktorin (https://github.com/encukou)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-3276",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-03T17:27:09.393265Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-03T17:27:19.179Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2026-06-03T19:18:17.828Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/06/03/15"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "CPython",
          "repo": "https://github.com/python/cpython",
          "vendor": "Python Software Foundation",
          "versions": [
            {
              "lessThan": "3.10.21",
              "status": "affected",
              "version": "0",
              "versionType": "python"
            },
            {
              "lessThan": "3.11.16",
              "status": "affected",
              "version": "3.11.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.12.14",
              "status": "affected",
              "version": "3.12.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.13.14",
              "status": "affected",
              "version": "3.13.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.14.6",
              "status": "affected",
              "version": "3.14.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.15.0b2",
              "status": "affected",
              "version": "3.15.0a1",
              "versionType": "python"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "Seokchan Yoon (https://github.com/ch4n3-yoon)"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Tim Peters (https://github.com/tim-one)"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "B\u00e9n\u00e9dikt Tran (https://github.com/picnixz)"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Serhiy Storchaka (https://github.com/serhiy-storchaka)"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Stan Ulbrych (https://github.com/StanFromIreland)"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "Seth Larson (https://github.com/sethmlarson)"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Petr Viktorin (https://github.com/encukou)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cspan\u003eunicodedata.normalize()\u003c/span\u003e can take excessive CPU time when processing\u003cbr\u003especially crafted Unicode input containing long runs of combining characters\u003cbr\u003ewith alternating Canonical Combining Class values.\u003cbr\u003eThis affects all normalization forms."
            }
          ],
          "value": "unicodedata.normalize() can take excessive CPU time when processing\nspecially crafted Unicode input containing long runs of combining characters\nwith alternating Canonical Combining Class values.\nThis affects all normalization forms."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "scenarios": [
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              "lang": "en",
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        "dateUpdated": "2026-08-13T00:28:05.768Z",
        "orgId": "28c92f92-d60d-412d-b760-e73465c3df22",
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      },
      "references": [
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          "tags": [
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          "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/PP5HB4K7727OBBM76KA2ILID76K3OZGZ/"
        },
        {
          "tags": [
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          "url": "https://github.com/python/cpython/pull/149080"
        },
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          ],
          "url": "https://github.com/python/cpython/issues/149079"
        },
        {
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          "url": "https://github.com/python/cpython/commit/6b505d1f41f8f3ea0fe5a4786d3a8fff1875cfc0"
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          "url": "https://github.com/python/cpython/commit/e322a1857084d521f79f45181b776f62e6acfc2c"
        }
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      "source": {
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    "datePublished": "2026-06-03T14:29:39.727Z",
    "dateReserved": "2026-02-26T15:19:46.862Z",
    "dateUpdated": "2026-08-13T00:28:05.768Z",
    "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.

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FKIE_CVE-2026-3276

CVE-2026-3276 (GCVE-0-2026-3276)

Tags

Sightings

Nomenclature

Related by attack behaviour