Erlang/OTP 22.2 < 27.3.4.18 / 28.0 < 28.5.0.7 / 29.0 < 29.1.1 TLS 1.3 Server Authentication Bypass (CVE-2026-89422)

critical Nessus Plugin ID 350080

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Synopsis

The remote host is missing a security update.

Description

The version of Erlang/OTP installed on the remote host is 22.2 prior to 27.3.4.18, 28.0 prior to 28.5.0.7, or 29.0 prior to 29.1.1. It is, therefore, affected by a vulnerability:

- Key Exchange without Entity Authentication vulnerability in Erlang/OTP ssl allows a peer that answers a TLS 1.3 client connection to impersonate the intended server. A pre_shared_key extension in the ServerHello that the client never offered causes the client to complete the handshake without validating the server's certificate, so ssl:connect returns {ok, Socket} against a peer holding no certificate, no private key and no prior session. Certificate path validation, verify_fun, hostname verification, partial_chain, CRL checking and OCSP stapling are all bypassed. The default client configuration is affected; clients restricted to TLS 1.2 are not. (CVE-2026-89422)

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

Solution

Upgrade to Erlang/OTP version 27.3.4.18, 28.5.0.7, or 29.1.1 or later.

Plugin Details

Severity: Critical

ID: 350080

File Name: erlang_otp_CVE-2026-89422.nasl

Version: 1.3

Type: Local

Agent: windows, macosx, unix

Family: Misc.

Published: 9/25/2026

Updated: 9/28/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.34

CVSS v2

Risk Factor: Medium

Base Score: 5.8

Temporal Score: 4.3

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

CVSS Score Source: CVE-2026-89422

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 7.9

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

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

CVSS v4

Risk Factor: Critical

Base Score: 9.3

Threat Score: 8

Threat Vector: CVSS:4.0/E:U

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

Vulnerability Information

CPE: cpe:/a:erlang:erlang%2fotp

Required KB Items: installed_sw/Erlang-OTP

Exploit Ease: No known exploits are available

Patch Publication Date: 9/22/2026

Vulnerability Publication Date: 9/22/2026

Reference Information

CVE: CVE-2026-89422

IAVA: 2026-A-1041

Detections

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