Linux Distros Unpatched Vulnerability : CVE-2026-18355

critical Nessus Plugin ID 343491

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base). In sasl_io_start_packet(), the wrapped-record length read from the wire is validated only against an upper bound. A small wire length (0, 1, or 2) produces an encrypted_buffer_count below the already-consumed encrypted_buffer_offset, causing an unsigned subtraction underflow in sasl_io_read_packet(). PR_Recv is then requested to read approximately 4 GiB into a 1024-byte heap buffer, resulting in a heap buffer overflow with attacker-controlled content. After a successful SASL bind with integrity protection (SSF > 0), a remote authenticated attacker can cause a denial of service or potentially achieve remote code execution. This flaw is distinct from CVE-2026-11774, whose fix only guards against upper-bound overflow.
(CVE-2026-18355)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: Critical

ID: 343491

File Name: unpatched_CVE_2026_18355.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 9/7/2026

Updated: 9/7/2026

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

Risk Information

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.4

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

CVSS Score Source: CVE-2026-18355

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9

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:U/RL:U/RC:C

Vulnerability Information

CPE: cpe:/o:centos:centos:7, cpe:/o:centos:centos:8, cpe:/o:redhat:enterprise_linux:10, cpe:/o:redhat:enterprise_linux:7, cpe:/o:redhat:enterprise_linux:8, cpe:/o:redhat:enterprise_linux:9, p-cpe:/a:centos:centos:389-ds-base-bdb, p-cpe:/a:centos:centos:389-ds-base-devel, p-cpe:/a:centos:centos:389-ds-base-legacy-tools, p-cpe:/a:centos:centos:389-ds-base-libs, p-cpe:/a:centos:centos:389-ds-base-snmp, p-cpe:/a:centos:centos:389-ds-base, p-cpe:/a:centos:centos:cockpit-389-ds, p-cpe:/a:centos:centos:python3-lib389, p-cpe:/a:redhat:enterprise_linux:389-ds-base-bdb, p-cpe:/a:redhat:enterprise_linux:389-ds-base-devel, p-cpe:/a:redhat:enterprise_linux:389-ds-base-legacy-tools, p-cpe:/a:redhat:enterprise_linux:389-ds-base-libs, p-cpe:/a:redhat:enterprise_linux:389-ds-base-snmp, p-cpe:/a:redhat:enterprise_linux:389-ds-base, p-cpe:/a:redhat:enterprise_linux:cockpit-389-ds, p-cpe:/a:redhat:enterprise_linux:python3-lib389

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 9/7/2026

Reference Information

CVE: CVE-2026-18355

Detections

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