CVE-2026-55568

5.9

MEDIUM CVSS 3.1

Guzzle: Silent HTTPS-Proxy Downgrade to Cleartext

Overview

Description

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.

Details

INFO

Published Date :

June 23, 2026, 4:17 p.m.

Last Modified :

June 26, 2026, 7:34 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]

Impact

Affected Products

The following products are affected by CVE-2026-55568 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID	Vendor	Product	Action
1	Guzzlephp	guzzle

: Total Affected Vendor : 1 | Products : 1

Scoring

CVSS Scores

The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.

Score	Version	Severity	Vector	Exploitability Score	Impact Score	Source
	CVSS					134c704f-9b21-4f2e-91b3-4a467353bcc0
	CVSS 3.1	MEDIUM				[email protected]

Solution

Update Guzzle to version 7.12.1 or later to fix cleartext proxy communication.

Update Guzzle to version 7.12.1 or later.
Ensure PHP cURL extension is updated if used.
Verify proxy configurations for encryption.

Public PoC/Exploit Available at Github

CVE-2026-55568 has a 3 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-55568.

URL	Resource
https://github.com/guzzle/guzzle/security/advisories/GHSA-wpwq-4j6v-78m3	Third Party Advisory

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-55568 is associated with the following CWEs:

CWE-311: Missing Encryption of Sensitive Data

CWE-319: Cleartext Transmission of Sensitive Information

CWE-636: Not Failing Securely ('Failing Open')

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-55568 weaknesses.

CAPEC-31: Accessing/Intercepting/Modifying HTTP Cookies Accessing/Intercepting/Modifying HTTP Cookies CAPEC-37: Retrieve Embedded Sensitive Data Retrieve Embedded Sensitive Data CAPEC-65: Sniff Application Code Sniff Application Code CAPEC-157: Sniffing Attacks Sniffing Attacks CAPEC-158: Sniffing Network Traffic Sniffing Network Traffic CAPEC-204: Lifting Sensitive Data Embedded in Cache Lifting Sensitive Data Embedded in Cache CAPEC-383: Harvesting Information via API Event Monitoring Harvesting Information via API Event Monitoring CAPEC-384: Application API Message Manipulation via Man-in-the-Middle Application API Message Manipulation via Man-in-the-Middle CAPEC-385: Transaction or Event Tampering via Application API Manipulation Transaction or Event Tampering via Application API Manipulation CAPEC-386: Application API Navigation Remapping Application API Navigation Remapping CAPEC-387: Navigation Remapping To Propagate Malicious Content Navigation Remapping To Propagate Malicious Content CAPEC-388: Application API Button Hijacking Application API Button Hijacking CAPEC-477: Signature Spoofing by Mixing Signed and Unsigned Content Signature Spoofing by Mixing Signed and Unsigned Content CAPEC-609: Cellular Traffic Intercept Cellular Traffic Intercept CAPEC-65: Sniff Application Code Sniff Application Code CAPEC-102: Session Sidejacking Session Sidejacking CAPEC-117: Interception Interception CAPEC-383: Harvesting Information via API Event Monitoring Harvesting Information via API Event Monitoring CAPEC-477: Signature Spoofing by Mixing Signed and Unsigned Content Signature Spoofing by Mixing Signed and Unsigned Content

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

hvenhlovskyi/insecurity-as-a-service

Demo project with vulnerabilities to test tools

PHP

Updated: 1 week, 4 days ago

0 stars 0 fork 0 watcher

Born at : July 10, 2026, 4:30 p.m. This repo has been linked 40 different CVEs too.

nvdigitalsolutions/mcp-ai-wpoos

NV Digital Open Operator System (NVoOS) is an Object-Oriented AI framework for WordPress connecting your data with OpenAI, Gemini, Anthropic, DeepSeek, Hugging Face, Cloudflare, OpenRouter & Ollama (Local) models. Create & manage AI Assistants that can interact with users, access WordPress (API) data, & perform as a MCP Server & Chat Agent

ai ai-agents ai-tools antropic-claude cloudflare-workers-ai google-gemini huggingface lm-studio mcp ollama-api ollama-client openai-api wordpress-plugin

PHP CSS JavaScript Shell HTML Python Dockerfile TypeScript Batchfile SCSS

Updated: 5 days, 15 hours ago

5 stars 1 fork 1 watcher

Born at : Oct. 22, 2025, 3:44 a.m. This repo has been linked 12 different CVEs too.

fabiodalez-dev/Pinakes

Complete Library Management System (ILS) - Circulation, OPAC, cataloging, reservations, loans, automatic notifications, plugin system, and Z39.50/SRU server

cataloging dewey-decimal ils isbn library-management opac open-source self-hosted biblioteche books catalog circulation digital-library ebooks library library-catalog koha-alternative

PHP CSS JavaScript TypeScript Shell

Updated: 3 days, 12 hours ago

81 stars 7 fork 7 watcher

Born at : Sept. 10, 2025, 9:28 p.m. This repo has been linked 4 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-55568 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-55568 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

Initial Analysis by [email protected]

Jun. 26, 2026

Action	Type	Old Value	New Value
Added	CPE Configuration		OR cpe:2.3:a:guzzlephp:guzzle::::::::* versions up to (excluding) 7.12.1
Added	Reference Type		GitHub, Inc.: https://github.com/guzzle/guzzle/security/advisories/GHSA-wpwq-4j6v-78m3 Types: Third Party Advisory

CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

Jun. 23, 2026

Action	Type	Old Value	New Value
Added	SSVC		{'id': 'CVE-2026-55568', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-23T15:44:34.695690Z'}

New CVE Received by [email protected]