Vulnerability-Lookup

OESA-2026-2605 (CVE-2026-45409)

Vulnerability from osv_openeuler – Published: 2026-06-05 11:11 – Updated: 2026-08-06 11:11 – Source website

Summary

python-idna security update

Details

A library to support the Internationalised Domain Names in Applications (IDNA) protocol as specified in RFC 5891 http://tools.ietf.org/html/rfc5891. This version of the protocol is often referred to as “IDNA2008” and can produce different results from the earlier standard from 2003.

Security Fix(es):

This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. Payloads such as "\u0660" * N or "\u30fb" * N + "\u6f22" utilize the valid_contexto function prior to length rejection, and for high values of N will take a long time to process.(CVE-2026-45409)

Severity

6.9 (Medium)


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

References

URL

Type

	https://www.openeuler.org/zh/security/security-bu…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2026-45409	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "noarch": [
          "python-idna-help-3.6-5.oe2403sp1.noarch.rpm",
          "python3-idna-3.6-5.oe2403sp1.noarch.rpm"
        ],
        "src": [
          "python-idna-3.6-5.oe2403sp1.src.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP1",
        "name": "python-idna",
        "purl": "pkg:rpm/openEuler/python-idna\u0026distro=openEuler-24.03-LTS-SP1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.6-5.oe2403sp1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "noarch": [
          "python-idna-help-3.6-5.oe2403sp3.noarch.rpm",
          "python3-idna-3.6-5.oe2403sp3.noarch.rpm"
        ],
        "src": [
          "python-idna-3.6-5.oe2403sp3.src.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP3",
        "name": "python-idna",
        "purl": "pkg:rpm/openEuler/python-idna\u0026distro=openEuler-24.03-LTS-SP3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.6-5.oe2403sp3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "noarch": [
          "python2-idna-2.10-4.oe2003sp4.noarch.rpm",
          "python3-idna-2.10-4.oe2003sp4.noarch.rpm"
        ],
        "src": [
          "python-idna-2.10-4.oe2003sp4.src.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:20.03-LTS-SP4",
        "name": "python-idna",
        "purl": "pkg:rpm/openEuler/python-idna\u0026distro=openEuler-20.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.10-4.oe2003sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "noarch": [
          "python3-idna-3.2-5.oe2203sp4.noarch.rpm"
        ],
        "src": [
          "python-idna-3.2-5.oe2203sp4.src.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:22.03-LTS-SP4",
        "name": "python-idna",
        "purl": "pkg:rpm/openEuler/python-idna\u0026distro=openEuler-22.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.2-5.oe2203sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "Medium"
  },
  "details": "A library to support the Internationalised Domain Names in Applications (IDNA) protocol as specified in RFC 5891 http://tools.ietf.org/html/rfc5891. This version of the protocol is often referred to as \u201cIDNA2008\u201d and can produce different results from the earlier standard from 2003.\r\n\r\nSecurity Fix(es):\n\nThis is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. Payloads such as \u0026quot;\\u0660\u0026quot; * N or \u0026quot;\\u30fb\u0026quot; * N + \u0026quot;\\u6f22\u0026quot; utilize the valid_contexto function prior to length rejection, and for high values of N will take a long time to process.(CVE-2026-45409)",
  "id": "OESA-2026-2605",
  "modified": "2026-08-06T11:11:32Z",
  "published": "2026-06-05T11:11:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2605"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45409"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "python-idna security update",
  "upstream": [
    "CVE-2026-45409"
  ]
}

CVE-2026-45409 (GCVE-0-2026-45409)

Vulnerability from cvelistv5 – Published: 2026-06-05 22:06 – Updated: 2026-06-08 16:34

Title

Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix

Summary

Internationalized Domain Names in Applications (IDNA) for Python provides support for Internationalized Domain Names in Applications (IDNA) and Unicode IDNA Compatibility Processing. In versions prior to 3.15, payloads such as `"\u0660" * N` or `"\u30fb" * N + "\u6f22"` utilize the `valid_contexto` function prior to length rejection, and for high values of `N` will take a long time to process. This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. A specially crafted argument to the `idna.encode()` function could consume significant resources. This may lead to a denial-of-service. Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support). A workaround is available. Domain names cannot exceed 253 characters in length. If this length limit is enforced prior to passing the domain to the `idna.encode()` function, it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.

Severity

6.9 (Medium)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-08 14:30 UTC

CWE

CWE-1333 - Inefficient Regular Expression Complexity

Assigner

GitHub_M mitre root Scorecard

References

1 reference

URL	Tags
https://github.com/kjd/idna/security/advisories/G…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
kjd	idna	Affected: < 3.15

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-45409",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-08T14:30:54.406761Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-08T16:34:00.295Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "idna",
          "vendor": "kjd",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.15"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Internationalized Domain Names in Applications (IDNA) for Python provides support for Internationalized Domain Names in Applications (IDNA) and Unicode IDNA Compatibility Processing. In versions prior to 3.15, payloads such as `\"\\u0660\" * N` or `\"\\u30fb\" * N + \"\\u6f22\"` utilize the `valid_contexto` function prior to length rejection, and for high values of `N` will take a long time to process. This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. A specially crafted argument to the `idna.encode()` function could consume significant resources. This may lead to a denial-of-service. Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support). A workaround is available. Domain names cannot exceed 253 characters in length. If this length limit is enforced prior to passing the domain to the `idna.encode()` function, it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/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"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-1333",
              "description": "CWE-1333: Inefficient Regular Expression Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-05T22:06:07.082Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/kjd/idna/security/advisories/GHSA-65pc-fj4g-8rjx",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/kjd/idna/security/advisories/GHSA-65pc-fj4g-8rjx"
        }
      ],
      "source": {
        "advisory": "GHSA-65pc-fj4g-8rjx",
        "discovery": "UNKNOWN"
      },
      "title": "Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-45409",
    "datePublished": "2026-06-05T22:06:07.082Z",
    "dateReserved": "2026-05-12T01:48:40.452Z",
    "dateUpdated": "2026-06-08T16:34:00.295Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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OESA-2026-2605 (CVE-2026-45409)

CVE-2026-45409 (GCVE-0-2026-45409)

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