Information disclosure through Python's "format" functionality in Zope AccessControl

Summary

AccessControl provides a general security framework for use in Zope. Python's "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. `AccessControl` already provides a safe variant for `str.format` and denies access to `string.Formatter`. However, `str.format_map` is still unsafe. Affected are all users who allow untrusted users to create `AccessControl` controlled Python code and execute it. A fix has been introduced in versions 4.4, 5.8 and 6.2. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Timeline

1. Sep 6, 2023, 5:58 PM UTCCVE published
2. Sep 26, 2024, 2:47 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Sep 26, 2024, 3:19 PM UTCRecord last updated

Affected versions

• zopefoundation AccessControl

  AccessControl: < 4.4, Zope: < 4.8.9

• accesscontrolPyPI

  fixed in 4.4

• zopePyPI

  fixed in 4.8.9

• accesscontrolPyPI

  From 5.0 · fixed in 5.8

• accesscontrolPyPI

  From 6.0 · fixed in 6.2

• zopePyPI

  From 5.0.0 · fixed in 5.8.4

• accesscontrolPyPI

  fixed in 4.4; From 5.0 · fixed in 5.8; From 6.0 · fixed in 6.2

• zopePyPI

  fixed in 4.8.9; From 5.0.0 · fixed in 5.8.4

References 2