Vulnerability-Lookup

UBUNTU-CVE-2026-97687 (CVE-2026-97687)

Vulnerability from osv_ubuntu – Published: 2026-09-29 16:17 – Updated: 2026-09-29 16:17 – Source website

Details

urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context, proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode, use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so later connections reusing the same context may connect to the HTTPS proxy without certificate verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after the effective proxy policy accepts the attacker's certificate. The impact is that the attacker can observe or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0.

Severity

7.6 (High)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-97687	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-97687	REPORT
	https://github.com/urllib3/urllib3/security/advis…	REPORT
	https://github.com/urllib3/urllib3/pull/5093	REPORT
	https://github.com/urllib3/urllib3/commit/07408ce…	REPORT
	https://github.com/urllib3/urllib3/commit/b644729…	REPORT
	https://github.com/urllib3/urllib3/releases/tag/2.8.0	REPORT

JSON

To clipboard

{
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      "ecosystem_specific": {
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          {
            "binary_name": "python-pip",
            "binary_version": "1.5.4-1ubuntu4+esm5"
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          }
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      "package": {
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        "name": "python-pip",
        "purl": "pkg:deb/ubuntu/python-pip@1.5.4-1ubuntu4+esm5?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
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            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.4.1-2",
        "1.5.4-1",
        "1.5.4-1ubuntu1",
        "1.5.4-1ubuntu3",
        "1.5.4-1ubuntu4",
        "1.5.4-1ubuntu4+esm1",
        "1.5.4-1ubuntu4+esm2",
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        "25.1.1+dfsg-1ubuntu2+esm2",
        "25.1.1+dfsg-1ubuntu2+esm3"
      ]
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  ],
  "aliases": [],
  "details": "urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context, proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode, use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so later connections reusing the same context may connect to the HTTPS proxy without certificate verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after the effective proxy policy accepts the attacker\u0027s certificate. The impact is that the attacker can observe or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0.",
  "id": "UBUNTU-CVE-2026-97687",
  "modified": "2026-09-29T16:17:00Z",
  "published": "2026-09-29T16:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-97687"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-97687"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-8988-9cw3-xx77"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/pull/5093"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/commit/07408cec79d1856d81bb42c74a904a24fdb9e465"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/commit/b6447295fff7b38fdffc67e0df9712d60cef3cc3"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/releases/tag/2.8.0"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-97687"
  ]
}

CVE-2026-97687 (GCVE-0-2026-97687)

Vulnerability from cvelistv5 – Published: 2026-09-29 15:30 – Updated: 2026-09-30 20:11

Title

urllib3: HTTPS proxy TLS configuration may be ignored or overridden

Summary

Severity

7.6 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-30 19:48 UTC

CWE

CWE-295 - Improper Certificate Validation
CWE-440 - Expected Behavior Violation

Assigner

GitHub_M mitre root Scorecard

References

5 references

URL	Tags
https://github.com/urllib3/urllib3/security/advis…	x_refsource_CONFIRM
https://github.com/urllib3/urllib3/pull/5093	x_refsource_MISC
https://github.com/urllib3/urllib3/commit/07408ce…	x_refsource_MISC
https://github.com/urllib3/urllib3/commit/b644729…	x_refsource_MISC
https://github.com/urllib3/urllib3/releases/tag/2.8.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
urllib3	urllib3	Affected: >= 1.26.0, < 2.8.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-97687",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-30T19:48:52.478378Z",
                "version": "2.0.3"
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        "providerMetadata": {
          "dateUpdated": "2026-09-30T20:11:09.721Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
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          "product": "urllib3",
          "vendor": "urllib3",
          "versions": [
            {
              "status": "affected",
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            }
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context, proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode, use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so later connections reusing the same context may connect to the HTTPS proxy without certificate verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after the effective proxy policy accepts the attacker\u0027s certificate. The impact is that the attacker can observe or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 7.6,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-295",
              "description": "CWE-295: Improper Certificate Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-440",
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              "lang": "en",
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        }
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          ],
          "url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-8988-9cw3-xx77"
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          "tags": [
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        {
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          "tags": [
            "x_refsource_MISC"
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          "url": "https://github.com/urllib3/urllib3/commit/07408cec79d1856d81bb42c74a904a24fdb9e465"
        },
        {
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      ],
      "source": {
        "advisory": "GHSA-8988-9cw3-xx77",
        "discovery": "UNKNOWN"
      },
      "title": "urllib3: HTTPS proxy TLS configuration may be ignored or overridden"
    }
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    "datePublished": "2026-09-29T15:30:27.136Z",
    "dateReserved": "2026-09-24T21:43:37.208Z",
    "dateUpdated": "2026-09-30T20:11:09.721Z",
    "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.

Action not permitted

UBUNTU-CVE-2026-97687 (CVE-2026-97687)

CVE-2026-97687 (GCVE-0-2026-97687)

Tags

Sightings

Nomenclature

Related by attack behaviour