CVE-2023-43804mediumCWE-200

CVE-2023-43804: medium-severity vulnerability in urllib3

`Cookie` HTTP header isn't stripped on cross-origin redirects

Published · Updated

Follow this CVE+ Monitor urllib3+ Monitor python-urllib3

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 5.9epss 1.4%
urllib3 is a user-friendly HTTP client library for Python. urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. This issue has been patched in urllib3 version 1.26.17 or 2.0.5.
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
Affected products
urllib3 · urllib3
Related CVEs — urllib3

In the same product, most dangerous first.

CVE-2026-21441HIGHurllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API)EPSS 2.9%CVE-2024-37891MEDIUMProxy-Authorization request header isn't stripped during cross-origin redirects in urllib3EPSS 1.1%CVE-2025-66471HIGHurllib3 Streaming API improperly handles highly compressed dataEPSS 0.7%CVE-2025-66418HIGHurllib3 allows an unbounded number of links in the decompression chainEPSS 0.7%CVE-2026-44432HIGHurllib3: Decompression-bomb safeguards bypassed in parts of the streaming APIEPSS 0.7%CVE-2025-50182MEDIUMurllib3 does not control redirects in browsers and Node.jsEPSS 0.6%