Is CVE-2026-67339 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-67339 being exploited in the wild.

How severe is CVE-2026-67339?

Medium severity, with a CVSS score of 5.3, published 1 August 2026.

Which products and versions are affected?

guzzlehttp/guzzle (Packagist) ECOSYSTEM:introduced=0,fixed=7.14.2.

Is there a fix for CVE-2026-67339?

Yes. guzzlehttp/guzzle (Packagist): upgrade to 7.14.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-67339 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-67339?

Check whether you run guzzlehttp/guzzle (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-67339: guzzlehttp Guzzle Proxy-Authorization header disclosure

CVE-2026-67339 · Severity: medium · CVSS 5.3 · Published 2026-08-01

Guzzle is a popular PHP HTTP client library used by applications to make web requests. A flaw in versions before 7.14.2 causes proxy authentication credentials (Proxy-Authorization headers) to be inadvertently sent to origin servers instead of being kept private for the proxy. An attacker controlling a web server that receives a redirected request could capture these credentials through access logs and potentially abuse the proxy to reach restricted resources or impersonate legitimate users.

Technologies: guzzlehttp/guzzle (Packagist). Vendors: Packagist.

Quick answers

Is CVE-2026-67339 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-67339 being exploited in the wild.
How severe is CVE-2026-67339?: Medium severity, with a CVSS score of 5.3, published 1 August 2026.
Which products and versions are affected?: guzzlehttp/guzzle (Packagist) ECOSYSTEM:introduced=0,fixed=7.14.2.
Is there a fix for CVE-2026-67339?: Yes. guzzlehttp/guzzle (Packagist): upgrade to 7.14.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-67339 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-67339?: Check whether you run guzzlehttp/guzzle (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

guzzlehttp/guzzle (Packagist): upgrade to 7.14.2 or later
```
composer require guzzlehttp/guzzle:^7.14.2
```

Technical details

The vulnerability is a sensitive information disclosure (CWE-200) in the cURL handlers (CurlHandler and CurlMultiHandler) of Guzzle. The root cause is that Guzzle incorrectly places Proxy-Authorization headers in cURL's origin header list (CURLOPT_HTTPHEADER) instead of the proxy-only list (CURLOPT_PROXYHEADER) when certain routing conditions occur: direct connections, proxy-bypassed requests (via no_proxy rules), or SOCKS proxies misclassified as direct. The vulnerability also occurs when redirect middleware re-evaluates proxy routing but fails to strip Proxy-Authorization. An attacker can exploit this by controlling an origin server (via redirect or direct access) to capture proxy credentials in access logs. Attack vector is network-based with no authentication required. Patch available in version 7.14.2.

Affected products

guzzlehttp Guzzle before 7.14.2

Identifiers

CVE-2026-67339
GHSA-94pj-82f3-465w

Timeline

2026-07-14: disclosed
2026-08-01: advisory: Published on NVD and VulnCheck
2026-07-14: patched: Fix released in version 7.14.2

References

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