guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-48998: 0.20% estimated exploitation activity in the next 30 days; percentile 9.66 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact guzzlehttp/psr7 improperly interpreted malformed Host header values when constructing request URIs from inbound request data. This issue concerns inbound request parsing and server request construction. It does not require serializing a PSR-7 request, and it is not part of the normal outbound request-sending path used by guzzlehttp/guzzle. A vulnerable flow is: 1. An attacker controls a raw HTTP request or server variable containing a Host value. 2. The Host value contains URI authority delimiters, such as trusted.example@evil.example. 3. guzzlehttp/psr7 uses that value to construct a URI. 4. The URI parser treats the portion before @ as userinfo and the portion after @ as the URI host. 5. The resulting PSR-7 request URI host differs from the original Host header value. For example, Host: trusted.example@evil.example can result in a PSR-7 URI whose host is evil.example, while the original Host header value remains trusted.example@evil.example. Applications are affected if they…

Published by the source

11 Jun 2026, 13:04 UTC

Last modified by the source

15 Jul 2026, 21:58 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-34xg-wgjx-8xph

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# Patch Next advisory brief: CVE-2026-48998

Advisory: guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation
IDs: CVE-2026-48998, GHSA-34xg-wgjx-8xph
Record: https://patchnext.com/advisories/cve-2026-48998 (revision 1, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: guzzlehttp/psr7 2.10.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist guzzlehttp/psr7: affected < 2.10.2; fixed in 2.10.2

## Suggested inspection (read-only)
- Packagist guzzlehttp/psr7: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on guzzlehttp/psr7.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-34xg-wgjx-8xph (GitHub-reviewed advisory GHSA-34xg-wgjx-8xph lists affected ranges: Packagist guzzlehttp/psr7 >=0 <2.10.2)

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