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Exposure of Sensitive Information to an Unauthorized Actor in urllib3

CVE-2026-44431

  • urllib3
High
8.2/10

Summary

When following cross-origin redirects for requests made using urllib3's high-level APIs, such as `urllib3.request()`, `PoolManager.request()`, and `ProxyManager.request()`, sensitive headers -- `Authorization`, `Cookie`, and `Proxy-Authorization` (defined in `Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT`) -- are stripped by default, as expected. However, cross-origin redirects followed from the low-level API via `ProxyManager.connection_from_url().urlopen(..., assert_same_host=False)` still forward these sensitive headers. This issue affects urllib3 versions 1.23 prior to 2.7.0.

  • LOW
  • NETWORK
  • NONE
  • UNCHANGED
  • NONE
  • NONE
  • LOW
  • NONE

CWE-200 - Information Exposure

An information exposure vulnerability is categorized as an information flow (IF) weakness, which can potentially allow unauthorized access to otherwise classified information in the application, such as confidential personal information (demographics, financials, health records, etc.), business secrets, and the application's internal environment.

References

Advisory Timeline

  • Published