CVE-2018-25091

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-10-15 · updated 2026-06-17
Weakness: CWE-601

Description

urllib3 before 1.24.2 does not remove the authorization HTTP header when following a cross-origin redirect (i.e., a redirect that differs in host, port, or scheme). This can allow for credentials in the authorization header to be exposed to unintended hosts or transmitted in cleartext. NOTE: this issue exists because of an incomplete fix for CVE-2018-20060 (which was case-sensitive).

Affected products

urllib3: before 1.24.2 — fixed in 1.24.2

How to fix

Upgrade to a fixed version: urllib3 1.24.2. Check the vendor advisory for mitigations.

References

https://github.com/urllib3/urllib3/commit/adb358f8e06865406d1f05e581a16cbea2136fbc
https://github.com/urllib3/urllib3/compare/1.24.1...1.24.2
https://github.com/urllib3/urllib3/issues/1510
https://github.com/urllib3/urllib3/commit/adb358f8e06865406d1f05e581a16cbea2136fbc
https://github.com/urllib3/urllib3/compare/1.24.1...1.24.2
https://github.com/urllib3/urllib3/issues/1510

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