A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate authentication, when the initial request is done using empty credentials. This can make user B's request get sent over user A's previously authenticated connection.

fedora FEDORA-2026-91d799048a: curl-8.18.0-13.fc44

The remote Fedora 45 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-663a2d0ba4 advisory.

    - fix HTTP/2 server push UAF (CVE-2026-18924)
    - fix Negotiate ambient user conn reuse (CVE-2026-19931)
    - remove test1701 - HTTP/2 Upgrade in a HTTP/1.1 POST request is no longer supported

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.

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

  - A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate
    authentication, when the initial request is done using empty credentials. This can make user B's request
    get sent over user A's previously authenticated connection. (CVE-2026-19931)

The version of curl installed on the remote host is 7.64.1 prior to 8.22.0. It is, therefore, affected by an information disclosure vulnerability:

  - A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate     authentication, when the initial request is done using empty credentials. This can make user B's request     get sent over user A's previously authenticated connection. (CVE-2026-19931)

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

The version of libcurl installed on the remote host is 7.64.1 prior to 8.22.0. It is, therefore, affected by an information disclosure vulnerability:

  - A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate     authentication, when the initial request is done using empty credentials. This can make user B's request     get sent over user A's previously authenticated connection. (CVE-2026-19931)

Note that Nessus has not tested for this issue 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.

  - A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate     authentication, when the initial request is done using empty credentials. This can make user B's request     get sent over user A's previously authenticated connection. (CVE-2026-19931)

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

ID	Name	Product	Family	Type	Severity
362930	Fedora 45 : curl (2026-663a2d0ba4)	Nessus	Fedora Local Security Checks	Local	critical
462118	Echo: curl: security update to 1:8.22.0-1+e1	Tenable Cloud Security	Echo Local Security Checks	Local	critical
462118	Echo: curl: security update to 1:8.22.0-1+e1	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	critical
342616	Curl 7.64.1 < 8.22.0 Negotiate Ambient User Connection Reuse	Nessus	Misc.	Local	medium
342615	libcurl 7.64.1 < 8.22.0 Negotiate Ambient User Connection Reuse	Nessus	Misc.	Local	medium
342437	Linux Distros Unpatched Vulnerability : CVE-2026-19931	Nessus	Misc.	Local	critical

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