CVE-2026-55568

Guzzle is an extensible PHP HTTP client. Prior to 7.12.1, in certain configurations, traffic expected to be protected by TLS on the hop to the proxy is transmitted in cleartext. Proxy authentication credentials (the Proxy-Authorization header, proxy userinfo in the proxy URL, or CURLOPT_PROXYUSERPWD) are sent without encryption, and the CONNECT target host and port for tunneled HTTPS requests are exposed. The built-in cURL handlers (GuzzleHttp\Handler\CurlHandler and GuzzleHttp\Handler\CurlMultiHandler, used by default whenever the PHP cURL extension is available) accept an https:// proxy. libcurl older than 7.50.2 silently treats an https:// proxy as a plaintext http:// proxy. The TLS connection to the proxy is never established, and the proxy leg is cleartext with no error or warning. An application is affected when it sends requests through one of the built-in cURL handlers, configures an https:// proxy expecting the proxy connection itself to be encrypted, and runs with libcurl older than 7.50.2. This vulnerability is fixed in 7.12.1.

CVSS v3 5.9 MEDIUM

5.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/guzzle/guzzle/security/advisories/GHSA-wpwq-4j6v-78m3

Configurations

No configuration.

History

23 Jun 2026, 16:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-23 16:17

Updated : 2026-06-23 17:57

NVD link : CVE-2026-55568

Mitre link : CVE-2026-55568

CVE.ORG link : CVE-2026-55568

JSON object : View

Products Affected

No product.

CWE

CWE-311

Missing Encryption of Sensitive Data

CWE-319

Cleartext Transmission of Sensitive Information

CWE-636

Not Failing Securely ('Failing Open')

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