Linux Distros Unpatched Vulnerability : CVE-2026-1965

critical Nessus Plugin ID 301847

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

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

- libcurl can in some circumstances reuse the wrong connection when asked to do an Negotiate-authenticated HTTP or HTTPS request. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criterion must first be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. One underlying reason being that Negotiate sometimes authenticates *connections* and not *requests*, contrary to how HTTP is designed to work. An application that allows Negotiate authentication to a server (that responds wanting Negotiate) with `user1:password1` and then does another operation to the same server also using Negotiate but with `user2:password2` (while the previous connection is still alive) - the second request wrongly reused the same connection and since it then sees that the Negotiate negotiation is already made, it just sends the request over that connection thinking it uses the user2 credentials when it is in fact still using the connection authenticated for user1... The set of authentication methods to use is set with `CURLOPT_HTTPAUTH`. Applications can disable libcurl's reuse of connections and thus mitigate this problem, by using one of the following libcurl options to alter how connections are or are not reused: `CURLOPT_FRESH_CONNECT`, `CURLOPT_MAXCONNECTS` and `CURLMOPT_MAX_HOST_CONNECTIONS` (if using the curl_multi API). (CVE-2026-1965)

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

Solution

There is no known solution at this time.

Plugin Details

Severity: Critical

ID: 301847

File Name: unpatched_CVE_2026_1965.nasl

Version: 1.1

Type: local

Agent: unix

Family: Misc.

Published: 3/11/2026

Updated: 3/11/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2026-1965

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:U/RC:C

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:curl, cpe:/o:debian:debian_linux:14.0, cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:13.0

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 3/11/2026

Reference Information

CVE: CVE-2026-1965

Detections

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