Detections
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Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : rxvt-unicode vulnerability (USN-8991-1)

high Nessus Plugin ID 375867

Synopsis

The remote Ubuntu host is missing a security update.

Description

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by a vulnerability as referenced in the USN-8991-1 advisory.

 It was discovered that rxvt-unicode incorrectly handled certain escape sequences. An attacker could possibly use this issue to execute arbitrary code if a user displayed specially crafted text in the terminal.

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

Note that Nessus has not tested for this issue 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-8991-1

Plugin Details

Severity: High

ID: 375867

File Name: ubuntu_USN-8991-1.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 11/4/2026

Updated: 11/4/2026

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

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 57.58

CVSS v2

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.1

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

CVSS Score Source: CVE-2021-33477

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.9

Vector: CVSS:3.0/AV:N/AC:L/PR:L/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:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:aterm-ml, p-cpe:/a:canonical:ubuntu_linux:aterm, p-cpe:/a:canonical:ubuntu_linux:rxvt-ml, p-cpe:/a:canonical:ubuntu_linux:rxvt-unicode-256color, p-cpe:/a:canonical:ubuntu_linux:rxvt-unicode-lite, p-cpe:/a:canonical:ubuntu_linux:rxvt-unicode-ml, p-cpe:/a:canonical:ubuntu_linux:rxvt-unicode, p-cpe:/a:canonical:ubuntu_linux:rxvt

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 11/3/2026

Vulnerability Publication Date: 5/20/2021

Reference Information

CVE: CVE-2021-33477

USN: 8991-1