CVE-2026-67339
Received Received - Intake

Guzzle HTTP Client Proxy-Authorization Header Exposure

Publication date: 2026-08-01

Last updated on: 2026-08-01

Assigner: VulnCheck

Description
guzzlehttp/guzzle versions before 7.14.2 fail to properly isolate Proxy-Authorization headers from origin servers in cURL handlers. Attackers can capture proxy credentials through origin server access logs when requests are redirected, bypassed, or sent through SOCKS proxies that Guzzle misclassifies as direct connections.

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Meta Information

Published
2026-08-01
Last Modified
2026-08-01
Generated
2026-08-01
AI Q&A
2026-08-01
EPSS Evaluated
N/A
NVD
CVE-2026-67339
EUVD
EUVD-2026-51854

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
guzzlehttp guzzle to 7.14.2 (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.

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Executive Summary

This vulnerability affects guzzlehttp/guzzle versions before 7.14.2. It fails to properly isolate Proxy-Authorization headers from origin servers in cURL handlers. Attackers can capture proxy credentials through origin server access logs when requests are redirected, bypassed, or sent through SOCKS proxies that Guzzle misclassifies as direct connections.

Detection Guidance

Check if your system uses guzzlehttp/guzzle versions before 7.14.2 by running: composer show guzzlehttp/guzzle. If the version is below 7.14.2, the system is vulnerable.

Impact Analysis

If you use an affected version of guzzlehttp/guzzle, attackers could steal proxy credentials. This could lead to unauthorized access to internal networks or sensitive data if those credentials are reused. It primarily affects applications making HTTP requests through proxies.

Mitigation Strategies

Upgrade guzzlehttp/guzzle to version 7.14.2 or later immediately. Use: composer require guzzlehttp/guzzle:^7.14.2. Review proxy configurations to ensure Proxy-Authorization headers are properly isolated.

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