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Erlang/OTP EUVDEUVD-2026-84338

| CVE-2026-89422 CRITICAL
Key Exchange without Entity Authentication (CWE-322)
2026-09-22 EEF
Authentication Bypass Otp Suse Erlang
9.3
CVSS 4.0 · Vendor: EEF
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Vendor (EEF) PRIMARY
9.3 CRITICAL
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
9.1 CRITICAL

Network-reachable and deterministic to trigger (AC:L) with no auth or interaction; server impersonation breaks confidentiality and integrity of the session (C:H/I:H) but does not affect availability (A:N).

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
SUSE
9.1 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Primary rating from Vendor (EEF).

CVSS VectorVendor: EEF

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

5
POC Analysis Generated
Sep 22, 2026 - 11:21 vuln.today
Metadata Corrected
Sep 22, 2026 - 09:40 vuln.today
tag: Erlang added
Metadata Corrected
Sep 22, 2026 - 09:40 vuln.today
tag: Microsoft removed
Analysis Generated
Sep 22, 2026 - 09:22 vuln.today
CVE Published
Sep 22, 2026 - 08:49 cve.org
CRITICAL 9.3

DescriptionCVE.org

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.

tls_client_connection_1_3:handle_server_hello/2 passes the received extension to tls_gen_connection_1_3:handle_resumption/2, which sets resumption = true on its mere presence without checking that the client offered a PSK. tls_handshake_1_3:get_pre_shared_key/4 meanwhile falls back to the all-zero "no PSK" value and keys the handshake with the ordinary non-PSK schedule, so the attacker's own ephemeral key suffices. The resumption flag then routes maybe_resumption/1 straight to wait_finished, skipping the certificate-handling states, so 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.

This issue affects OTP from OTP 22.2 before OTP 27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to ssl from 9.5 before 11.2.12.13, 11.6.0.6, and 11.7.7.

AnalysisAI

Erlang/OTP's ssl application in affected releases (OTP 22.2 through the fixed 27.3.4.18, 28.5.0.7 and 29.1.1) will complete a TLS 1.3 client handshake against any peer that answers with an unsolicited pre_shared_key extension, allowing that peer to impersonate the intended server while holding no certificate, no private key and no prior session. Because the bogus resumption flag short-circuits certificate handling, ssl:connect returns {ok, Socket} even though certificate path validation, verify_fun, hostname verification, partial_chain, CRL checking and OCSP stapling are all skipped; an unauthenticated network-positioned attacker (man-in-the-middle, hijacked route/DNS, or a server the client is lured into contacting) can exploit this, and clients restricted to TLS 1.2 are not affected. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

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Vulnerability AssessmentAI

Exploitation Requires the victim to be an Erlang/OTP application acting as a TLS 1.3 client via ssl:connect in its default configuration (the default client config IS affected). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuine high-priority vulnerability, not a high-CVSS-but-low-impact artifact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Vendor-released patch: upgrade to OTP 27.3.4.18, OTP 28.5.0.7 or OTP 29.1.1 (ssl 11.2.12.13, 11.6.0.6 and 11.7.7 respectively), which carry the fixes in commits 21b8a1b0ad0adf200682b3854bc50114ab2b8c62, afec5156361bb50d3607c7c1a453c19b9149b324, 98c66c858113949c4262d26cd7d426c4b09d2b35 and fd1d9d07fc92ec0d59f96dfb66182195882bb7dd; full details are in the advisory at https://github.com/erlang/otp/security/advisories/GHSA-rgxr-4g4w-j875 and https://cna.erlef.org/cves/CVE-2026-89422.html. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours, identify all systems running Erlang/OTP versions 22.2 through 27.3.4.17, 28.5.0.6, and 29.1.0 (affected releases) and determine if they act as TLS 1.3 clients; if so, consider temporarily disabling TLS 1.3 client capability or restricting connections to TLS 1.2 as an interim mitigation. …

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected

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EUVD-2026-84338 vulnerability details – vuln.today
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