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Vulnerability record · CVE-2018-25091 · published 15 October 2023

CVE-2018-25091: Python urllib3 open redirect vulnerability

Python · Urllib3

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).

6.1 CVSS 3.1 Medium EPSS 0.52% · top 58.4% CWE-601 · Open redirect
6.1CVSS 3.1 base score
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

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).

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/urllib3/urllib3/commit/adb358f8e06865406d1f05e581a16cbea2136fbc Patch
https://github.com/urllib3/urllib3/compare/1.24.1...1.24.2 Patch
https://github.com/urllib3/urllib3/issues/1510 Issue TrackingPatchVendor Advisory
https://github.com/urllib3/urllib3/commit/adb358f8e06865406d1f05e581a16cbea2136fbc Patch
https://github.com/urllib3/urllib3/compare/1.24.1...1.24.2 Patch
https://github.com/urllib3/urllib3/issues/1510 Issue TrackingPatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2018-25091), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.