Guzzle is an extensible PHP HTTP client. Prior to 7.12.1, in certain configurations, traffic expected to be protected by TLS on the hop to the proxy is transmitted in cleartext. Proxy authentication credentials (the Proxy-Authorization header, proxy userinfo in the proxy URL, or CURLOPT_PROXYUSERPWD) are sent without encryption, and the CONNECT target host and port for tunneled HTTPS requests are exposed. The built-in cURL handlers (GuzzleHttp\Handler\CurlHandler and GuzzleHttp\Handler\CurlMultiHandler, used by default whenever the PHP cURL extension is available) accept an https:// proxy. libcurl older than 7.50.2 silently treats an https:// proxy as a plaintext http:// proxy. The TLS connection to the proxy is never established, and the proxy leg is cleartext with no error or warning. An application is affected when it sends requests through one of the built-in cURL handlers, configures an https:// proxy expecting the proxy connection itself to be encrypted, and runs with libcurl older than 7.50.2. This vulnerability is fixed in 7.12.1.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-ee50c21f92 advisory.

    33.0.6 Release

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-5afe6630dc advisory.

    33.0.6 Release

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Guzzle is an extensible PHP HTTP client. Prior to 7.12.1, in certain configurations, traffic expected to     be protected by TLS on the hop to the proxy is transmitted in cleartext. Proxy authentication credentials     (the Proxy-Authorization header, proxy userinfo in the proxy URL, or CURLOPT_PROXYUSERPWD) are sent     without encryption, and the CONNECT target host and port for tunneled HTTPS requests are exposed. The     built-in cURL handlers (GuzzleHttp\Handler\CurlHandler and GuzzleHttp\Handler\CurlMultiHandler, used by     default whenever the PHP cURL extension is available) accept an https:// proxy. libcurl older than 7.50.2     silently treats an https:// proxy as a plaintext http:// proxy. The TLS connection to the proxy is never     established, and the proxy leg is cleartext with no error or warning. An application is affected when it     sends requests through one of the built-in cURL handlers, configures an https:// proxy expecting the proxy     connection itself to be encrypted, and runs with libcurl older than 7.50.2. This vulnerability is fixed in     7.12.1. (CVE-2026-55568)

Note that Nessus relies on the presence of the package as reported by the vendor.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - Guzzle is an extensible PHP HTTP client. Prior to 7.12.1, in certain configurations, traffic expected to
    be protected by TLS on the hop to the proxy is transmitted in cleartext. Proxy authentication credentials
    (the Proxy-Authorization header, proxy userinfo in the proxy URL, or CURLOPT_PROXYUSERPWD) are sent
    without encryption, and the CONNECT target host and port for tunneled HTTPS requests are exposed. The
    built-in cURL handlers (GuzzleHttp\Handler\CurlHandler and GuzzleHttp\Handler\CurlMultiHandler, used by
    default whenever the PHP cURL extension is available) accept an https:// proxy. libcurl older than 7.50.2
    silently treats an https:// proxy as a plaintext http:// proxy. The TLS connection to the proxy is never
    established, and the proxy leg is cleartext with no error or warning. An application is affected when it
    sends requests through one of the built-in cURL handlers, configures an https:// proxy expecting the proxy
    connection itself to be encrypted, and runs with libcurl older than 7.50.2. This vulnerability is fixed in
    7.12.1. (CVE-2026-55568)

ID	Name	Product	Family	Severity
325136	Fedora 44 : nextcloud (2026-ee50c21f92)	Nessus	Fedora Local Security Checks	high
325111	Fedora 43 : nextcloud (2026-5afe6630dc)	Nessus	Fedora Local Security Checks	high
321828	Linux Distros Unpatched Vulnerability : CVE-2026-55568	Nessus	Misc.	medium
443607	SCA: security update for guzzlehttp/guzzle (GHSA-wpwq-4j6v-78m3)	Tenable Cloud Security	SCA Checks	medium
443607	SCA: security update for guzzlehttp/guzzle (GHSA-wpwq-4j6v-78m3)	Tenable Self-Hosted Container Security	SCA Checks	medium

Detections

Analytics

CVE-2026-55568

medium

Tenable Plugins

high

high

medium

medium

medium