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libcurl 7.10.6 < 8.21.0 Cross-Origin Digest Auth State Leak

critical Nessus Plugin ID 323007

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Synopsis

The remote host has a program that is affected by a credential disclosure vulnerability.

Description

The version of libcurl installed on the remote host is 7.10.6 prior to 8.21.0. It is, therefore, affected by a credential disclosure vulnerability:

 - Successfully using libcurl with Digest authentication and then changing the origin to a different host for a second transfer, reusing the same handle, makes libcurl wrongly pass on the Authorization header meant for the first host. (CVE-2026-11856)

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

Solution

Upgrade libcurl to version 8.21.0 or later.

See Also

https://curl.se/docs/CVE-2026-11856.html

Plugin Details

Severity: Critical

ID: 323007

File Name: libcurl_CVE-2026-11856.nasl

Version: 1.3

Type: Local

Agent: windows, macosx, unix

Family: Misc.

Published: 6/26/2026

Updated: 7/8/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Continuous Assessment, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.9

Percentile: 96.92

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 3.9

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

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:haxx:libcurl

Required KB Items: installed_sw/libcurl

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 6/24/2026

Vulnerability Publication Date: 6/24/2026

Reference Information

CVE: CVE-2026-11856

IAVA: 2026-A-0627