CVE-2026-44431 — urllib3: Sensitive headers forwarded across origins in proxied low-level redirects

Affected: urllib3

urllib3 is an HTTP client library for Python. From 1.23 to before 2.7.0, 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 vulnerability is fixed in 2.7.0.

USN-8379-1 — python-urllib3 vulnerabilities

Affected: Ubuntu:22.04:LTS: python-urllib3, Ubuntu:24.04:LTS: python-urllib3, Ubuntu:25.10: python-urllib3, Ubuntu:26.04:LTS: python-urllib3

It was discovered that urllib3 incorrectly handled cross-origin redirects in ProxyManager. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-44431)

It was discovered that urllib3 incorrectly handled decompression of specially crafted responses. A remote attacker could possibly use this issue to cause urllib3 to consume resources, leading to a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-44432)

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CVE-2026-44431 — urllib3: Sensitive headers forwarded across origins in proxied low-level redirects

USN-8379-1 — python-urllib3 vulnerabilities