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CVE-2026-89422— TLS 1.3 client skips server authentication when ServerHello carries an unsolicited pre_shared_key extension

Quick assessment

Affected
Erlang OTP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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

CVSS 9.3 · Critical EPSS 0.37% · P31

Affected Version Matrix 3

VendorProduct Version RangeStatus
Erlang OTP 22.2< * affected
9.5< * affected
21b8a1b0ad0adf200682b3854bc50114ab2b8c62< * affected
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I. Basic Information for CVE-2026-89422

Vulnerability Information

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Vulnerability Title
TLS 1.3 client skips server authentication when ServerHello carries an unsolicited pre_shared_key extension
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
未进行实体认证的密钥交换
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Erlang OTP 22.2 ~ * cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 9.5 ~ * cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 21b8a1b0ad0adf200682b3854bc50114ab2b8c62 ~ * cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-89422

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III. Intelligence Information for CVE-2026-89422

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Patches & Fixes for CVE-2026-89422 (4)

Other References for CVE-2026-89422 (3)

Same Patch Batch · Erlang · 2026-09-22 · 3 CVEs total

CVE-2026-65634 8.2 HIGH Superlinear CPU denial of service in Erlang/OTP ASN.1 OBJECT IDENTIFIER decoder
CVE-2026-68956 7.1 HIGH SSH daemon allocates unbounded idle session channels, bypassing max_channels

IV. Related Vulnerabilities

Same product: OTP
Same vendor: Erlang
Same weakness: CWE-322

V. Comments for CVE-2026-89422

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