Guzzle: Noncanonical host can bypass host-based checks

Exploitation

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

CVSS

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

EPSS

• CVE-2026-69246: 0.37% estimated exploitation activity in the next 30 days; percentile 30.98 (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 In affected versions, Guzzle gives a transport the request URI as text and supplies the Host header separately. The cURL handlers set CURLOPTURL to the URI exactly as written and push that Host into CURLOPTHTTPHEADER; 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 it would have generated. In http://127.0.0.%31/ the URI host is one filtervar() rejects 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 it exposes of the response. The same divergence moves Guzzle's own decisions onto a spelling the transport does not use:…

Published by the source

3 Aug 2026, 21:07 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-v5mv-p594-2x33

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-v5mv-p594-2x33

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# Patch Next advisory brief: CVE-2026-69246

Advisory: Guzzle: Noncanonical host can bypass host-based checks
IDs: CVE-2026-69246, GHSA-v5mv-p594-2x33
Record: https://patchnext.com/advisories/cve-2026-69246 (revision 2, 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: High (CVSS 7.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: guzzlehttp/guzzle 8.0.1, 7.15.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist guzzlehttp/guzzle: affected < 7.15.2; >= 8.0.0, < 8.0.1; fixed in 7.15.2, 8.0.1

## Suggested inspection (read-only)
- Packagist guzzlehttp/guzzle: 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/guzzle.
- 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://osv.dev/vulnerability/GHSA-v5mv-p594-2x33 (OSV record GHSA-v5mv-p594-2x33 lists affected ranges: Packagist guzzlehttp/guzzle >=0 =8.0.0 <8.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-v5mv-p594-2x33 (GitHub-reviewed advisory GHSA-v5mv-p594-2x33 lists affected ranges: Packagist guzzlehttp/guzzle >=0 =8.0.0 <8.0.1)

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