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Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : HAProxy vulnerabilities (USN-8459-1)

critical Nessus Plugin ID 322262

Synopsis

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

Description

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8459-1 advisory.

 It was discovered that HAProxy incorrectly handled the FCGI demultiplexer record length field. A remote attacker could possibly use this issue to cause incorrect request routing, response smuggling, or other memory safety issues. (CVE-2026-55203)

 It was discovered that HAProxy failed to validate the return value of the HPACK dynamic table defragmentation function when memory was exhausted. A remote attacker could possibly use this issue to cause HAProxy to crash, resulting in a denial of service. (CVE-2026-55204)

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 haproxy and / or vim-haproxy packages.

See Also

https://ubuntu.com/security/notices/USN-8459-1

Plugin Details

Severity: Critical

ID: 322262

File Name: ubuntu_USN-8459-1.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 6/23/2026

Updated: 6/23/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

CVSS v2

Risk Factor: Medium

Base Score: 6.1

Temporal Score: 4.5

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

CVSS Score Source: CVE-2026-55203

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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

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

CVSS v4

Risk Factor: Critical

Base Score: 9

Threat Score: 6.5

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:25.10, p-cpe:/a:canonical:ubuntu_linux:haproxy, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:vim-haproxy, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts

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

Exploit Ease: No known exploits are available

Patch Publication Date: 6/22/2026

Vulnerability Publication Date: 6/18/2026

Reference Information

CVE: CVE-2026-55203, CVE-2026-55204

USN: 8459-1