CVE-2026-55553
Received Received - Intake

urllib Credential Leak via Redirect Reuse

Publication date: 2026-08-25

Last updated on: 2026-08-25

Assigner: GitHub, Inc.

Description
urllib is an HTTP client for Node.js that supports authentication, redirects, timeouts, and other request features. Prior to 4.9.1 and 2.44.1, urllib follows redirects through followRedirect but reuses caller-supplied options across origins. In src/HttpClient.ts, #requestInternal recursively calls this.#requestInternal(nextUrl.href, options, requestContext), causing options.headers and auth or digestAuth values to be reused when the redirect target has a different scheme, host, or port. Authorization, Cookie, Proxy-Authorization, x-api-key, x-auth-token, and x-access-token can therefore be sent to an attacker-controlled redirected origin, exposing credentials intended for the original origin and potentially allowing reuse against the original partner API or related services. No user interaction is required. This issue is fixed in versions 2.44.1 and 4.9.1.

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Meta Information

Published
2026-08-25
Last Modified
2026-08-25
Generated
2026-08-25
AI Q&A
2026-08-25
EPSS Evaluated
N/A
NVD
CVE-2026-55553
EUVD
EUVD-2026-65613

Affected Vendors & Products

Showing 5 associated CPEs
Vendor Product Version / Range
node-modules urllib 2.44.1
node-modules urllib 4.9.1
node-modules urllib From 4.0.0 (inc) to 4.9.1 (exc)
node-modules urllib to 2.44.1 (exc)
urllib urllib to 4.9.1 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-200 The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
CWE-522 The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.
CWE-201 The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

Attack-Flow Graph

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Executive Summary

urllib is an HTTP client for Node.js that follows redirects but reuses caller-supplied options across different origins. This means sensitive headers like Authorization, Cookie, or Proxy-Authorization are forwarded to attacker-controlled redirected origins when the redirect target has a different scheme, host, or port. The vulnerability allows credentials intended for the original origin to be exposed to unintended domains without requiring user interaction.

Detection Guidance

To detect this vulnerability, check if your system uses urllib versions between 4.0.0-4.9.0 or <=2.44.0. Run: npm list urllib or npm list -g urllib. If affected versions are found, update immediately to 4.9.1 or 2.44.1 or later.

Impact Analysis

This vulnerability can expose sensitive authentication data such as API keys, tokens, or cookies to unintended third-party domains during redirects. Attackers could exploit this by redirecting requests to malicious servers, potentially reusing leaked credentials against the original API or related services. No user interaction is required for exploitation.

Compliance Impact

This vulnerability could lead to unauthorized exposure of sensitive data, violating compliance requirements under GDPR (data protection) and HIPAA (protected health information). Unauthorized credential leakage may result in data breaches, triggering regulatory penalties and legal consequences for organizations failing to protect user data.

Mitigation Strategies

Immediately update urllib to version 4.9.1 or 2.44.1 or later using npm update urllib or npm install urllib@latest. Review applications using urllib for cross-origin redirect handling to ensure no credentials are leaked.

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