Vulnerability-Lookup

GHSA-PQ59-9FQ7-M886

Vulnerability from github – Published: 2026-09-17 16:30 – Updated: 2026-09-17 16:30

Summary

Zope AccessControl vulnerable to information disclosure through Python string `format` and `format_map` functions

Details

Impact

Python's string format functionality allows someone controlling the format string to "read" objects accessible (recursively) via attribute access and subscription from accessible objects. Those attribute accesses and subscriptions use Python's full blown getattr and getitem, not the policy restricted AccessControl variants _getattr_ and _getitem_. This can lead to critical information disclosure.

The AccessControl package already guards against direct access to the formatting functions on string instances, but these mitigations did not cover subclasses of str.

Affected are all users who allow untrusted users to create AccessControl controlled Python code and execute it.

Patches

A fix was published with version 7.4.

Workarounds

There is no workaround.

Severity

6.8 (Medium)


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

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "AccessControl"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-77401"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-693"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-17T16:30:37Z",
    "nvd_published_at": "2026-09-16T15:17:46Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nPython\u0027s string `format` functionality allows someone controlling the format string to \"read\" objects accessible (recursively) via attribute access and subscription from accessible objects. Those attribute accesses and subscriptions use Python\u0027s full blown `getattr` and `getitem`, not the policy restricted `AccessControl` variants `_getattr_` and `_getitem_`. This can lead to critical information disclosure.\n\nThe `AccessControl` package already guards against direct access to the formatting functions on string instances, but these mitigations did not cover subclasses of `str`.\n\nAffected are all users who allow untrusted users to create AccessControl controlled Python code and execute it.\n\n### Patches\nA fix was published with version 7.4.\n\n### Workarounds\nThere is no workaround.",
  "id": "GHSA-pq59-9fq7-m886",
  "modified": "2026-09-17T16:30:37Z",
  "published": "2026-09-17T16:30:37Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-pq59-9fq7-m886"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77401"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/AccessControl/commit/f980450eea416718be62847f34dfd51822938e43"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/zopefoundation/AccessControl"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/AccessControl/releases/tag/7.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Zope AccessControl vulnerable to information disclosure through Python string `format` and `format_map` functions"
}

CVE-2026-77401 (GCVE-0-2026-77401)

Vulnerability from cvelistv5 – Published: 2026-09-16 14:28 – Updated: 2026-09-16 18:35

Title

Zope AccessControl: Information disclosure through Python string `format` and `format_map` functions

Summary

Zope AccessControl provides a general security framework for use in Zope. Prior to 7.4, applications that allow untrusted users to create and execute AccessControl-controlled Python code do not safely guard str.format and str.format_map when those methods are reached through a str subclass. In both ImplPython.py and cAccessControl.c, Python formatting can recursively access attributes and subscriptions using unrestricted getattr and getitem behavior instead of the policy-restricted getattr and getitem operations. A controlled format string can therefore disclose objects reachable from values available to the formatting operation. This issue is fixed in version 7.4.

Severity

6.8 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-16 18:18 UTC

CWE

CWE-693 - Protection Mechanism Failure

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/zopefoundation/AccessControl/s…	x_refsource_CONFIRM
https://github.com/zopefoundation/AccessControl/c…	x_refsource_MISC
https://github.com/zopefoundation/AccessControl/r…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
zopefoundation	AccessControl	Affected: < 7.4

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-77401",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-16T18:18:37.466466Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-16T18:35:46.823Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "AccessControl",
          "vendor": "zopefoundation",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 7.4"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Zope AccessControl provides a general security framework for use in Zope. Prior to 7.4, applications that allow untrusted users to create and execute AccessControl-controlled Python code do not safely guard str.format and str.format_map when those methods are reached through a str subclass. In both ImplPython.py and cAccessControl.c, Python formatting can recursively access attributes and subscriptions using unrestricted getattr and getitem behavior instead of the policy-restricted getattr and getitem operations. A controlled format string can therefore disclose objects reachable from values available to the formatting operation. This issue is fixed in version 7.4."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.8,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "HIGH",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-693",
              "description": "CWE-693: Protection Mechanism Failure",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-16T14:28:01.186Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-pq59-9fq7-m886",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-pq59-9fq7-m886"
        },
        {
          "name": "https://github.com/zopefoundation/AccessControl/commit/f980450eea416718be62847f34dfd51822938e43",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/zopefoundation/AccessControl/commit/f980450eea416718be62847f34dfd51822938e43"
        },
        {
          "name": "https://github.com/zopefoundation/AccessControl/releases/tag/7.4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/zopefoundation/AccessControl/releases/tag/7.4"
        }
      ],
      "source": {
        "advisory": "GHSA-pq59-9fq7-m886",
        "discovery": "UNKNOWN"
      },
      "title": "Zope AccessControl: Information disclosure through Python string `format` and `format_map` functions"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-77401",
    "datePublished": "2026-09-16T14:28:01.186Z",
    "dateReserved": "2026-08-20T19:55:27.023Z",
    "dateUpdated": "2026-09-16T18:35:46.823Z",
    "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.

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.