What’s Vulnerable › Vulnerabilities

CVE-2026-67339: guzzlehttp/guzzle before 7.14.2 Proxy-Authorization Header Disclosure

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-01 · updated 2026-10-08
• Weakness: CWE-200

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.

Affected products

• Packagist Guzzlehttp/Guzzle: before 7.14.2; 4.0.0, 4.0.0-rc.1, 4.0.0-rc.2, 4.0.1, 4.0.2, 4.1.0 (+166) — fixed in 7.14.2
• guzzle: before 7.14.2 — fixed in 7.14.2

How to fix

Upgrade to a fixed version: Packagist Guzzlehttp/Guzzle 7.14.2; guzzle 7.14.2. Check the vendor advisory for mitigations.

References

• https://github.com/guzzle/guzzle/security/advisories/GHSA-94pj-82f3-465w
• https://www.vulncheck.com/advisories/guzzlehttp-guzzle-before-proxy-authorization-header-disclosure

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