Guzzle up to 7.15.1/8.0.0 cURL filter_var redirect

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Guzzle up to 7.15.1/8.0.0. This affects the function filter_var of the component cURL Handler. The manipulation leads to redirect. This vulnerability is listed as CVE-2026-69246. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Guzzle up to 7.15.1/8.0.0 and classified as problematic. This issue affects the function filter_var of the component cURL Handler. The manipulation with an unknown input leads to a redirect vulnerability. Using CWE to declare the problem leads to CWE-601. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. Impacted is integrity. The summary by CVE is:

Guzzle is an extensible PHP HTTP client. Prior to 7.15.2 and 8.0.1, Guzzle gives a transport the request URI as text and supplies the Host header separately. The cURL handlers set CURLOPT_URL to the URI exactly as written and push that Host into CURLOPT_HTTPHEADER; StreamHandler does the same through fopen(). libcurl then parses the authority itself, percent-decoding it and, on an IDN-capable build, applying IDNA mapping, and uses the result to resolve, connect, name the TLS peer and address a proxy CONNECT, while the supplied Host suppresses the aligned one libcurl would have generated. For a URI host written as 127.0.0.%31, filter_var() rejects the host as an IP literal, yet libcurl decodes it to 127.0.0.1 and reaches loopback with no DNS lookup while the server receives Host: 127.0.0.%31. An attacker who influences a fetched URI can therefore reach a host the application's checks excluded and read whatever the host exposes of the response. The same divergence moves Guzzle's own decisions onto a spelling the transport does not use: no_proxy selects proxy routing from the literal host, and RedirectMiddleware decides from it whether to strip Authorization and Cookie. Exploitation requires the application to build a request URI from untrusted input and to make a host decision before handing it to Guzzle. This issue is fixed in versions 7.15.2 and 8.0.1.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-69246 since 08/03/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1204.001 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 331888 (Linux Distros Unpatched Vulnerability : CVE-2026-69246), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 7.15.2 or 8.0.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (331888). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Guzzle

Version

• 7.15.0
• 7.15.1
• 8.0

Website

• Product: https://github.com/guzzle/guzzle/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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