How severe is CVE-2018-25091?

CVE-2018-25091 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2018-25091 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-25091?

CVE-2018-25091 affects Python Urllib3. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-25091?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-25091 published?

CVE-2018-25091 was published on 2023-10-15 and last updated on 2026-06-17.

CVE-2018-25091

CVE-2018-25091 is a medium-severity vulnerability in Python Urllib3 with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-601.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
EPSS exploit prediction: 1% (40th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-601
Affected product: Python Urllib3
Published: 2023-10-15
Last modified: 2026-06-17

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).

Frequently asked questions

What is CVE-2018-25091?: 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).
How severe is CVE-2018-25091?: CVE-2018-25091 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2018-25091 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-25091?: CVE-2018-25091 affects Python Urllib3. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-25091?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-25091 published?: CVE-2018-25091 was published on 2023-10-15 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*

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