CVE-2025-50181
Description
A flaw was found in urllib3. The PoolManager class allows redirects to be disabled by configuring retries in a specific manner, effectively bypassing intended HTTP redirection behavior. A network attacker can leverage this configuration to manipulate request flows and disrupt service. This bypass occurs through improper handling of retry parameters during PoolManager instantiation. This issue can reult in a denial of service or unintended data exposure due to altered request destinations.
Statement
A flaw was found in the urllib3 library where it could be tricked into disclosing the Proxy-Authorization header to a destination server when a CONNECT tunnel is used. An attacker can set up a malicious redirect to a crafted URL, which, when followed by the client application, will cause the Proxy-Authorization header to be sent to the attacker-controlled server. This leaks sensitive credentials for the proxy. The impact is primarily on confidentiality. While urllib3 is a ubiquitous component, the vulnerability requires a specific scenario where a user is connecting to a proxy that requires authentication and is redirected to a malicious endpoint. This lowers the exploitability compared to a direct, unauthenticated remote attack, thus, warranting a Moderate severity rating.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | 6.1 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | Low | None | N/A |
| User Interaction | None | Required | N/A |
| Scope | Unchanged | Changed | N/A |
| Confidentiality | High | Low | N/A |
| Integrity Impact | None | Low | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity
The user may be redirected to an untrusted page that contains malware which may then compromise the user's system. In some cases, an open redirect can also enable the immediate download of a file without the user's permission, because the redirection to an external site may lead to endpoints on those sites that automatically trigger a download action ("drive-by download" [REF-1478]). This will expose the user to extensive risk. The user's interaction with the web server may also be compromised if the malware conducts keylogging or other attacks that steal credentials, personally identifiable information (PII), or other important data.
Access Control,Confidentiality,Other
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity; Other
By modifying the URL value to a malicious site, an attacker may successfully launch a phishing scam. The user may be subjected to phishing attacks by being redirected to an untrusted page. The phishing attack may point to an attacker controlled web page that appears to be a trusted web site. The phishers may then steal the user's credentials and then use these credentials to access the legitimate web site. Because the server name in the modified link is identical to the original site, phishing attempts have a more trustworthy appearance.
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