CVE-2024-37891Network attack vector

Proxy credential disclosure via cross-origin redirects

Published Jun 17, 2024 · Updated Nov 3, 2025

Credential disclosure in urllib3 before 1.26.19 and 2.0.0 through 2.2.1 allows attackers to read proxy credentials via cross-origin redirects. Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT omits Proxy-Authorization, so PoolManager forwards that authentication header when following a redirect to another origin. Exploitation requires direct header configuration outside ProxyManager, enabled redirects, and either an HTTP origin or a malicious redirect from the proxy or target.

CVSS severity4.4
Medium
EPSS probability1.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Credential disclosure in urllib3 before 1.26.19 and 2.0.0 through 2.2.1 allows attackers to read proxy credentials via cross-origin redirects. Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT omits Proxy-Authorization, so PoolManager forwards that authentication header when following a redirect to another origin. Exploitation requires direct header configuration outside ProxyManager, enabled redirects, and either an HTTP origin or a malicious redirect from the proxy or target.

The record

CVE
CVE-2024-37891
Published
Jun 17, 2024
Updated
Nov 3, 2025
Vendor
urllib3
Product
urllib3
Classifications
CWE-669
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Jun 17, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.26.19
  2. Affected versionversion=>= 2.0.0, < 2.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

urllib3 · urllib3version=< 1.26.19; version=>= 2.0.0, < 2.2.2

Published CVSS scores

4.4GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-669Incorrect Resource Transfer Between Spheres

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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