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Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : curl vulnerabilities (USN-8820-1)

critical Nessus Plugin ID 350699

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Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8820-1 advisory.

 Eunsoo Kim discovered that curl incorrectly handled SASL negotiation for LDAP authentication in certain circumstances. A machine-in-the-middle attacker could possibly use this issue to bypass peer validation.
 This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-13608)

 Stephan Zeisberg discovered that curl incorrectly handled HTTP/2 Server Push streams when sharing connections between handles. A remote attacker could possibly use this issue to cause curl to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-18924)

 Stanislav Fort discovered that curl incorrectly managed the lifetime of pooled TLS connections when using the multi interface. An attacker could possibly use this issue to cause curl to crash, resulting in a denial of service, or execute arbitrary code. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-80229)

 Stanislav Fort discovered that curl did not properly enforce public key pinning when certificate verification was disabled in certain circumstances. A remote attacker could possibly use this issue to bypass pinning checks and cause curl to accept connections that should have been rejected.
 (CVE-2026-80230)

 Stanislav Fort discovered that curl incorrectly handled the Secure attribute of cookies in certain circumstances. A remote attacker could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-80255)

 Stanislav Fort discovered that curl did not properly enforce Public Suffix List boundaries when handling cookies in certain circumstances. A remote attacker could possibly use this issue to cause cookies to be sent to unrelated domains, resulting in sensitive information being exposed. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS.
 (CVE-2026-82209)

 Ady Elouej discovered that curl did not clear proxy authentication state between requests when reusing a handle with environment-variable proxy configuration. A remote attacker could possibly use this issue to obtain sensitive credentials. This issue was previously fixed in USN-8487-1, but that fix was incomplete for Ubuntu 16.04 LTS. (CVE-2026-8927)

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

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 affected packages.

See Also

https://ubuntu.com/security/notices/USN-8820-1

Plugin Details

Severity: Critical

ID: 350699

File Name: ubuntu_USN-8820-1.nasl

Version: 1.2

Type: Local

Agent: unix

Published: 9/25/2026

Updated: 9/28/2026

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: 4.3

Percentile: 53.44

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 7.4

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

CVSS Score Source: CVE-2026-18924

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 8.2

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

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:curl, p-cpe:/a:canonical:ubuntu_linux:libcurl3-gnutls, p-cpe:/a:canonical:ubuntu_linux:libcurl3-nss, p-cpe:/a:canonical:ubuntu_linux:libcurl3, p-cpe:/a:canonical:ubuntu_linux:libcurl3t64-gnutls, p-cpe:/a:canonical:ubuntu_linux:libcurl4, p-cpe:/a:canonical:ubuntu_linux:libcurl4t64

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/24/2026

Vulnerability Publication Date: 9/24/2026

Reference Information

CVE: CVE-2026-13608, CVE-2026-18924, CVE-2026-80229, CVE-2026-80230, CVE-2026-80255, CVE-2026-82209

USN: 8820-1