Guzzle up to 7.15.0 RedirectMiddleware referer information disclosure

Summaryinfo

A vulnerability identified as problematic has been detected in Guzzle up to 7.15.0. The affected element is an unknown function of the component RedirectMiddleware. This manipulation of the argument referer causes information disclosure. This vulnerability appears as CVE-2026-67354. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability has been found in Guzzle up to 7.15.0 and classified as problematic. Affected by this vulnerability is some unknown functionality of the component RedirectMiddleware. The manipulation of the argument referer with an unknown input leads to a information disclosure vulnerability. The CWE definition for the vulnerability is CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. As an impact it is known to affect confidentiality. The summary by CVE is:

guzzlehttp/guzzle versions before 7.15.1 contain an information disclosure vulnerability in RedirectMiddleware. When the optional allow_redirects.referer setting is enabled, the middleware copies the URI fragment (the portion after '#') from the referring request into the generated Referer header when following a same-scheme redirect (e.g., HTTPS to HTTPS). An attacker who controls the redirect destination can read this fragment from the incoming Referer header, potentially disclosing one-time login secrets, access tokens, state values, or other sensitive client data to a server never meant to receive it. The referer setting is disabled by default. Fixed in 7.15.1, which strips the fragment before generating the Referer value.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-67354 since 07/29/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

Upgrading to version 7.15.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-51825). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

• Guzzle

Version

• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15.0

Website

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

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Be aware that VulDB is the high quality source for vulnerability data.

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