CVE-2026-3298 (GCVE-0-2026-3298)

Vulnerability from cvelistv5 – Published: 2026-04-21 14:45 – Updated: 2026-08-13 00:27
VLAI
Title
Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes
Summary
The method "sock_recvfrom_into()" of "asyncio.ProacterEventLoop" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected.
Severity
8.8 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-04-21 19:15 UTC
CWE
Assigner
PSF CNA under the mitre root
CNA scorecard B 80/100 over 27 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Python Software Foundation CPython Affected: 0 , < 3.11.16 (python)
Affected: 3.12.0 , < 3.12.14 (python)
Affected: 3.13.0 , < 3.13.14 (python)
Affected: 3.14.0a1 , < 3.14.5rc1 (python)
Affected: 3.15.0a1 , < 3.15.0b1 (python)
guessed Create a notification for this product.
Credits
GGAutomaton (https://github.com/GGAutomaton) Victor Stinner (https://github.com/vstinner) Seth Larson (https://github.com/sethmlarson)
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-3298",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-21T19:15:36.206348Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-21T19:15:44.557Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "CPython",
          "repo": "https://github.com/python/cpython",
          "vendor": "Python Software Foundation",
          "versions": [
            {
              "lessThan": "3.11.16",
              "status": "affected",
              "version": "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": "3.14.5rc1",
              "status": "affected",
              "version": "3.14.0a1",
              "versionType": "python"
            },
            {
              "lessThan": "3.15.0b1",
              "status": "affected",
              "version": "3.15.0a1",
              "versionType": "python"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "GGAutomaton (https://github.com/GGAutomaton)"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Victor Stinner (https://github.com/vstinner)"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "Seth Larson (https://github.com/sethmlarson)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "type": "text/html",
              "value": "The method \"sock_recvfrom_into()\" of \"asyncio.ProacterEventLoop\" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected."
            }
          ],
          "value": "The method \"sock_recvfrom_into()\" of \"asyncio.ProacterEventLoop\" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "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:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-787",
              "description": "CWE-787 Out-of-bounds write",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-13T00:27:55.667Z",
        "orgId": "28c92f92-d60d-412d-b760-e73465c3df22",
        "shortName": "PSF"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/pull/148809"
        },
        {
          "tags": [
            "issue-tracking"
          ],
          "url": "https://github.com/python/cpython/issues/148808"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/KWTPIQBOOOUNQP7UFSLBI437NJDFLA3F/"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/1274766d3c29007ab77245a72abbf8dce2a9db4d"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/27522b7d6e6588f03e61099dd858cd5a9314e2f2"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/95633d2aad4721e25e4dfd9f43dfb6e1edcbd741"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/6c8b85b3f1d83d5697ec19880960e1eacee56688"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/f5ca38739241fe7a40a4b116d5a8a1364dd6fea7"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "28c92f92-d60d-412d-b760-e73465c3df22",
    "assignerShortName": "PSF",
    "cveId": "CVE-2026-3298",
    "datePublished": "2026-04-21T14:45:01.919Z",
    "dateReserved": "2026-02-26T20:12:47.041Z",
    "dateUpdated": "2026-08-13T00:27:55.667Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-3298",
      "date": "2026-10-18",
      "epss": "0.00604",
      "percentile": "0.47812"
    },
    "microsoft_vex": {
      "current_release_date": "2026-04-30T01:52:58.000Z",
      "cve": "CVE-2026-3298",
      "id": "msrc_CVE-2026-3298",
      "initial_release_date": "2026-04-02T00:00:00.000Z",
      "product_status:known_not_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-3298.json",
      "version": "3"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "CPython",
                "repo": "https://github.com/python/cpython",
                "vendor": "Python Software Foundation",
                "versions": [
                  {
                    "lessThan": "3.11.16",
                    "status": "affected",
                    "version": "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": "3.14.5rc1",
                    "status": "affected",
                    "version": "3.14.0a1",
                    "versionType": "python"
                  },
                  {
                    "lessThan": "3.15.0b1",
                    "status": "affected",
                    "version": "3.15.0a1",
                    "versionType": "python"
                  }
                ]
              }
            ],
            "source": "cna@python.org"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "The method \"sock_recvfrom_into()\" of \"asyncio.ProacterEventLoop\" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected."
          }
        ],
        "id": "CVE-2026-3298",
        "lastModified": "2026-08-13T01:16:52.990",
        "metrics": {
          "cvssMetricV40": [
            {
              "cvssData": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "NONE",
                "attackVector": "NETWORK",
                "availabilityRequirement": "NOT_DEFINED",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "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:N/PR:N/UI:N/VC:L/VI:L/VA:H/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": "HIGH",
                "vulnConfidentialityImpact": "LOW",
                "vulnIntegrityImpact": "LOW",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "source": "cna@python.org",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-3298",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-21T19:15:36.206348Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-04-21T15:16:37.047",
        "references": [
          {
            "source": "cna@python.org",
            "url": "https://github.com/python/cpython/commit/1274766d3c29007ab77245a72abbf8dce2a9db4d"
          },
          {
            "source": "cna@python.org",
            "url": "https://github.com/python/cpython/commit/27522b7d6e6588f03e61099dd858cd5a9314e2f2"
          },
          {
            "source": "cna@python.org",
            "url": "https://github.com/python/cpython/commit/6c8b85b3f1d83d5697ec19880960e1eacee56688"
          },
          {
            "source": "cna@python.org",
            "url": "https://github.com/python/cpython/commit/95633d2aad4721e25e4dfd9f43dfb6e1edcbd741"
          },
          {
            "source": "cna@python.org",
            "url": "https://github.com/python/cpython/commit/f5ca38739241fe7a40a4b116d5a8a1364dd6fea7"
          },
          {
            "source": "cna@python.org",
            "url": "https://github.com/python/cpython/issues/148808"
          },
          {
            "source": "cna@python.org",
            "url": "https://github.com/python/cpython/pull/148809"
          },
          {
            "source": "cna@python.org",
            "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/KWTPIQBOOOUNQP7UFSLBI437NJDFLA3F/"
          }
        ],
        "sourceIdentifier": "cna@python.org",
        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-787"
              }
            ],
            "source": "cna@python.org",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "current_release_date": "2026-05-06T20:21:46+00:00",
      "cve": "CVE-2026-3298",
      "id": "CVE-2026-3298",
      "initial_release_date": "2026-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3298.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-3298",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-04-21T19:15:36.206348Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-04-21T19:15:41.466Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "CPython",
              "repo": "https://github.com/python/cpython",
              "vendor": "Python Software Foundation",
              "versions": [
                {
                  "lessThan": "3.11.16",
                  "status": "affected",
                  "version": "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": "3.14.5rc1",
                  "status": "affected",
                  "version": "3.14.0a1",
                  "versionType": "python"
                },
                {
                  "lessThan": "3.15.0b1",
                  "status": "affected",
                  "version": "3.15.0a1",
                  "versionType": "python"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "reporter",
              "value": "GGAutomaton (https://github.com/GGAutomaton)"
            },
            {
              "lang": "en",
              "type": "remediation reviewer",
              "value": "Victor Stinner (https://github.com/vstinner)"
            },
            {
              "lang": "en",
              "type": "coordinator",
              "value": "Seth Larson (https://github.com/sethmlarson)"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "type": "text/html",
                  "value": "The method \"sock_recvfrom_into()\" of \"asyncio.ProacterEventLoop\" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected."
                }
              ],
              "value": "The method \"sock_recvfrom_into()\" of \"asyncio.ProacterEventLoop\" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected."
            }
          ],
          "metrics": [
            {
              "cvssV4_0": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "NONE",
                "attackVector": "NETWORK",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "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:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N",
                "version": "4.0",
                "vulnAvailabilityImpact": "HIGH",
                "vulnConfidentialityImpact": "LOW",
                "vulnIntegrityImpact": "LOW",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-787",
                  "description": "CWE-787 Out-of-bounds write",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-13T00:27:55.667Z",
            "orgId": "28c92f92-d60d-412d-b760-e73465c3df22",
            "shortName": "PSF"
          },
          "references": [
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/python/cpython/pull/148809"
            },
            {
              "tags": [
                "issue-tracking"
              ],
              "url": "https://github.com/python/cpython/issues/148808"
            },
            {
              "tags": [
                "vendor-advisory"
              ],
              "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/KWTPIQBOOOUNQP7UFSLBI437NJDFLA3F/"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/python/cpython/commit/1274766d3c29007ab77245a72abbf8dce2a9db4d"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/python/cpython/commit/27522b7d6e6588f03e61099dd858cd5a9314e2f2"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/python/cpython/commit/95633d2aad4721e25e4dfd9f43dfb6e1edcbd741"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/python/cpython/commit/6c8b85b3f1d83d5697ec19880960e1eacee56688"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/python/cpython/commit/f5ca38739241fe7a40a4b116d5a8a1364dd6fea7"
            }
          ],
          "source": {
            "discovery": "UNKNOWN"
          },
          "title": "Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes",
          "x_generator": {
            "engine": "cvelib 1.8.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "28c92f92-d60d-412d-b760-e73465c3df22",
        "assignerShortName": "PSF",
        "cveId": "CVE-2026-3298",
        "datePublished": "2026-04-21T14:45:01.919Z",
        "dateReserved": "2026-02-26T20:12:47.041Z",
        "dateUpdated": "2026-08-13T00:27:55.667Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    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.