Detections
Analytics

CentOS 9 : curl-7.76.1-44.el9

critical Nessus Plugin ID 367946

Synopsis

The remote CentOS host is missing one or more security updates for curl.

Description

The remote CentOS Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the curl-7.76.1-44.el9 build changelog.

 - Successfully using libcurl to do a transfer to a specific HTTP origin (`hostA`) with **Digest** authentication and then changing the origin to a different one (`hostB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Authorization:` header field meant for `hostA`, to `hostB`. (CVE-2026-11856)

 - 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 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)

 - When an OAuth2 bearer token is used for an HTTP(S) transfer, and that transfer performs a redirect to a second URL, curl could leak that token to the second hostname under some circumstances. If the hostname that the first request is redirected to has information in the used .netrc file, with either of the `machine` or `default` keywords, curl would pass on the bearer token set for the first host also to the second one. (CVE-2026-3783)

 - A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not. (CVE-2026-8286)

 - libcurl might in some circumstances reuse the wrong connection when asked to do Negotiate-authenticated ones, even when they are set to use different services. 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 criteria must 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 services. (CVE-2026-8458)

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

Solution

Update the CentOS 9 Stream curl package.

See Also

https://kojihub.stream.centos.org/koji/buildinfo?buildID=132265

Plugin Details

Severity: Critical

ID: 367946

File Name: centos9_curl-7_76_1-44_132265.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 10/20/2026

Updated: 10/20/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.9

Percentile: 96.42

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.8

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

CVSS Score Source: CVE-2026-11856

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

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:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:centos:centos:9, p-cpe:/a:centos:centos:curl-minimal, p-cpe:/a:centos:centos:curl, p-cpe:/a:centos:centos:libcurl-devel, p-cpe:/a:centos:centos:libcurl-minimal, p-cpe:/a:centos:centos:libcurl

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/CentOS/release, Host/CentOS/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 10/11/2026

Vulnerability Publication Date: 3/11/2026

Reference Information

CVE: CVE-2026-11856, CVE-2026-1965, CVE-2026-3783, CVE-2026-8286, CVE-2026-8458, CVE-2026-8924, CVE-2026-8927, CVE-2026-8932, CVE-2026-9547

IAVA: 2026-A-0237-S, 2026-A-0627-S