guzzle psr7 up to 2.10.1 Message::parseRequest missing initialization

Summaryinfo

A vulnerability labeled as problematic has been found in guzzle psr7 up to 2.10.1. Affected is the function Message::parseRequest. The manipulation results in missing initialization. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is known as CVE-2026-48998. It is possible to launch the attack remotely. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, was found in guzzle psr7 up to 2.10.1. Affected is the function Message::parseRequest. The manipulation with an unknown input leads to a missing initialization vulnerability. CWE is classifying the issue as CWE-456. The product does not initialize critical variables, which causes the execution environment to use unexpected values. This is going to have an impact on confidentiality. CVE summarizes:

guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Versions prior to 2.10.2 contain improper Host header validation when parsing raw HTTP request messages and when deriving a server request URI from server variables. An attacker can provide a malformed Host header containing URI authority delimiters, such as `[email protected]`. When the Host value is used to construct a URI, the malformed value can be reinterpreted as URI userinfo and host. This can cause the PSR-7 request URI host to differ from the original Host header value. Applications are affected if they parse attacker-controlled raw HTTP requests with `GuzzleHttp\Psr7\Message::parseRequest()` or the legacy 1.x `GuzzleHttp\Psr7\parse_request()` function, or if they build server requests from attacker-controlled server variables, then rely on the resulting URI host for routing, allow-list checks, or forwarding decisions. In affected forwarding or gateway scenarios, this may cause requests or credentials to be sent to an unintended host. The issue is patched in `2.10.2`. `1.x` is end-of-life and will not receive a patch. Some workarounds are available. Validate the `Host` header as `uri-host [ ":" port ]` before calling `Message::parseRequest()` or legacy `parse_request()` on untrusted HTTP request data, or before deriving routing and forwarding decisions from a parsed request URI. Reject Host values containing userinfo, path, query, or fragment delimiters.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-48998 since 05/27/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

Upgrading to version 2.10.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-36239). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• guzzle

Name

• psr7

Version

• 2.10.0
• 2.10.1

Support

• end of life

Website

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

CPE 2.3info

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CPE 2.2info

• 🔒
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Once again VulDB remains the best source for vulnerability data.

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