Vulnerability-Lookup

OESA-2023-1936 (CVE-2023-30861)

Vulnerability from osv_openeuler – Published: 2023-12-22 11:06 – Updated: 2026-08-06 11:06 – Source website

Summary

python-flask security update

Details

Flask is a lightweight WSGI web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. It began as a simple wrapper around Werkzeug and Jinja and has become one of the most popular Python web application frameworks.

Security Fix(es):

The application must be hosted behind a caching proxy that does not strip cookies or ignore responses with cookies.
The application sets session.permanent = True
The application does not access or modify the session at any point during a request.
SESSION_REFRESH_EACH_REQUEST enabled (the default).
The application does not set a Cache-Control header to indicate that a page is private or should not be cached.

This happens because vulnerable versions of Flask only set the Vary: Cookie header when the session is accessed or modified, not when it is refreshed (re-sent to update the expiration) without being accessed or modified. This issue has been fixed in versions 2.3.2 and 2.2.5.(CVE-2023-30861)

Severity

7.5 (High)


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

References

URL

Type

	https://www.openeuler.org/en/security/safety-bull…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2023-30861	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "noarch": [
          "python2-flask-1.1.2-5.oe2003sp4.noarch.rpm",
          "python3-flask-1.1.2-5.oe2003sp4.noarch.rpm"
        ],
        "src": [
          "python-flask-1.1.2-5.oe2003sp4.src.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:20.03-LTS-SP4",
        "name": "python-flask",
        "purl": "pkg:rpm/openEuler/python-flask\u0026distro=openEuler-20.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.1.2-5.oe2003sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "High"
  },
  "details": "Flask is a lightweight WSGI web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. It began as a simple wrapper around Werkzeug and Jinja and has become one of the most popular Python web application frameworks.\r\n\r\nSecurity Fix(es):\r\n\r\nFlask is a lightweight WSGI web application framework. When all of the following conditions are met, a response containing data intended for one client may be cached and subsequently sent by the proxy to other clients. If the proxy also caches `Set-Cookie` headers, it may send one client\u0026apos;s `session` cookie to other clients. The severity depends on the application\u0026apos;s use of the session and the proxy\u0026apos;s behavior regarding cookies. The risk depends on all these conditions being met.\r\n\r\n1. The application must be hosted behind a caching proxy that does not strip cookies or ignore responses with cookies.\n2. The application sets `session.permanent = True`\n3. The application does not access or modify the session at any point during a request.\n4. `SESSION_REFRESH_EACH_REQUEST` enabled (the default).\n5. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\r\n\r\nThis happens because vulnerable versions of Flask only set the `Vary: Cookie` header when the session is accessed or modified, not when it is refreshed (re-sent to update the expiration) without being accessed or modified. This issue has been fixed in versions 2.3.2 and 2.2.5.(CVE-2023-30861)",
  "id": "OESA-2023-1936",
  "modified": "2026-08-06T11:06:23Z",
  "published": "2023-12-22T11:06:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2023-1936"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-30861"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "python-flask security update",
  "upstream": [
    "CVE-2023-30861"
  ]
}

CVE-2023-30861 (GCVE-0-2023-30861)

Vulnerability from cvelistv5 – Published: 2023-05-02 17:04 – Updated: 2025-02-13 16:49

Title

Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header

Summary

Flask is a lightweight WSGI web application framework. When all of the following conditions are met, a response containing data intended for one client may be cached and subsequently sent by the proxy to other clients. If the proxy also caches `Set-Cookie` headers, it may send one client's `session` cookie to other clients. The severity depends on the application's use of the session and the proxy's behavior regarding cookies. The risk depends on all these conditions being met. 1. The application must be hosted behind a caching proxy that does not strip cookies or ignore responses with cookies. 2. The application sets `session.permanent = True` 3. The application does not access or modify the session at any point during a request. 4. `SESSION_REFRESH_EACH_REQUEST` enabled (the default). 5. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached. This happens because vulnerable versions of Flask only set the `Vary: Cookie` header when the session is accessed or modified, not when it is refreshed (re-sent to update the expiration) without being accessed or modified. This issue has been fixed in versions 2.3.2 and 2.2.5.

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-01-30 16:29 UTC

CWE

CWE-539 - Use of Persistent Cookies Containing Sensitive Information

Assigner

GitHub_M mitre root

References

8 references

URL	Tags
https://github.com/pallets/flask/security/advisor…	x_refsource_CONFIRM
https://github.com/pallets/flask/commit/70f906c51…	x_refsource_MISC
https://github.com/pallets/flask/commit/afd63b161…	x_refsource_MISC
https://github.com/pallets/flask/releases/tag/2.2.5	x_refsource_MISC
https://github.com/pallets/flask/releases/tag/2.3.2	x_refsource_MISC
https://www.debian.org/security/2023/dsa-5442
https://security.netapp.com/advisory/ntap-2023081…
https://lists.debian.org/debian-lts-announce/2023…

Impacted products

1 product

Vendor	Product	Version
pallets	flask	Affected: >= 2.3.0, < 2.3.2 Affected: < 2.2.5

Show details on NVD website

JSON

To clipboard

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            "tags": [
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            "url": "https://github.com/pallets/flask/releases/tag/2.2.5"
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            "url": "https://security.netapp.com/advisory/ntap-20230818-0006/"
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        "title": "CVE Program Container"
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        "metrics": [
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            "other": {
              "content": {
                "id": "CVE-2023-30861",
                "options": [
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        },
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          "versions": [
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        }
      ],
      "metrics": [
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          "cvssV3_1": {
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          "name": "https://github.com/pallets/flask/commit/70f906c51ce49c485f1d355703e9cc3386b1cc2b",
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    "state": "PUBLISHED"
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}

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.

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.