Vulnerability-Lookup

PYSEC-2026-2268

Vulnerability from pysec - Published: 2026-03-18 00:16 - Updated: 2026-07-13 05:51

Details

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to set_tlsext_servername_callback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.

Severity

5.3 (Medium)


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

Impacted products

Name	purl
pyopenssl	pkg:pypi/pyopenssl

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {},
      "package": {
        "ecosystem": "PyPI",
        "name": "pyopenssl",
        "purl": "pkg:pypi/pyopenssl"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.14"
            },
            {
              "fixed": "26.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.14",
        "0.15",
        "0.15.1",
        "16.0.0",
        "16.1.0",
        "16.2.0",
        "17.0.0",
        "17.1.0",
        "17.2.0",
        "17.3.0",
        "17.4.0",
        "17.5.0",
        "18.0.0",
        "19.0.0",
        "19.1.0",
        "20.0.0",
        "20.0.1",
        "21.0.0",
        "22.0.0",
        "22.1.0",
        "23.0.0",
        "23.1.0",
        "23.1.1",
        "23.2.0",
        "23.3.0",
        "24.0.0",
        "24.1.0",
        "24.2.1",
        "24.3.0",
        "25.0.0",
        "25.1.0",
        "25.2.0",
        "25.3.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27448",
    "GHSA-vp96-hxj8-p424"
  ],
  "details": "pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.",
  "id": "PYSEC-2026-2268",
  "modified": "2026-07-13T05:51:07.105913Z",
  "published": "2026-03-18T00:16:19.107Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-27448 (GCVE-0-2026-27448)

Vulnerability from cvelistv5 – Published: 2026-03-17 23:24 – Updated: 2026-03-18 20:18

Title

pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback

Summary

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.

Severity

1.7 (Low)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-636 - Not Failing Securely ('Failing Open')

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/pyca/pyopenssl/security/adviso…	x_refsource_CONFIRM
https://github.com/pyca/pyopenssl/commit/d41a8147…	x_refsource_MISC
https://github.com/pyca/pyopenssl/blob/358cbf29c4…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
pyca	pyopenssl	Affected: >= 0.14.0, < 26.0.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-27448",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-18T20:17:52.492201Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-18T20:18:08.768Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "pyopenssl",
          "vendor": "pyca",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.14.0, \u003c 26.0.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 1.7,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-636",
              "description": "CWE-636: Not Failing Securely (\u0027Failing Open\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-17T23:24:30.661Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424"
        },
        {
          "name": "https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0"
        },
        {
          "name": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27"
        }
      ],
      "source": {
        "advisory": "GHSA-vp96-hxj8-p424",
        "discovery": "UNKNOWN"
      },
      "title": "pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-27448",
    "datePublished": "2026-03-17T23:24:30.661Z",
    "dateReserved": "2026-02-19T17:25:31.100Z",
    "dateUpdated": "2026-03-18T20:18:08.768Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-VP96-HXJ8-P424

Vulnerability from github – Published: 2026-03-16 15:15 – Updated: 2026-03-19 18:28

Summary

pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback

Details

If a user provided callback to set_tlsext_servername_callback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it.

Unhandled exceptions now result in rejecting the connection.

Credit to Leury Castillo for reporting this issue.

Severity

1.7 (Low)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "pyopenssl"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.14.0"
            },
            {
              "fixed": "26.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27448"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-636"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-16T15:15:43Z",
    "nvd_published_at": "2026-03-18T00:16:19Z",
    "severity": "LOW"
  },
  "details": "If a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it.\n\nUnhandled exceptions now result in rejecting the connection.\n\nCredit to **Leury Castillo** for reporting this issue.",
  "id": "GHSA-vp96-hxj8-p424",
  "modified": "2026-03-19T18:28:02Z",
  "published": "2026-03-16T15:15:43Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27448"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pyca/pyopenssl"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U",
      "type": "CVSS_V4"
    }
  ],
  "summary": "pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback"
}

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.

Action not permitted

PYSEC-2026-2268

CVE-2026-27448 (GCVE-0-2026-27448)

GHSA-VP96-HXJ8-P424

Tags

Sightings

Nomenclature