guzzle psr7 up to 2.12.2 Host Validator getHost assertion

Summaryinfo

A vulnerability categorized as critical has been discovered in guzzle psr7 up to 2.12.2. Affected by this issue is the function Uri::assertValidHost/Uri::getHost of the component Host Validator. Such manipulation leads to assertion. This vulnerability is documented as CVE-2026-59882. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in guzzle psr7 up to 2.12.2 and classified as critical. Affected by this issue is the function Uri::assertValidHost/Uri::getHost of the component Host Validator. The manipulation with an unknown input leads to a assertion vulnerability. Using CWE to declare the problem leads to CWE-617. The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary. Impacted is confidentiality, integrity, and availability. CVE summarizes:

guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Prior to 2.12.3, Uri::assertValidHost() does not reject URI host components containing authority delimiters, embedded ports, or malformed IPv6 brackets, allowing Uri::getHost() to disagree with the URI authority used for security or routing decisions. This issue is fixed in version 2.12.3.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-59882 since 07/07/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 325842 (Linux Distros Unpatched Vulnerability : CVE-2026-59882), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.12.3 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (325842). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• guzzle

Name

• psr7

Version

• 2.12.0
• 2.12.1
• 2.12.2

Website

• Product: https://github.com/guzzle/psr7/

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Once again VulDB remains the best source for vulnerability data.

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