Erlang OTP up to 29.0.2 ClientHello improper validation of specified quantity in input

Summaryinfo

A vulnerability was found in Erlang OTP up to 29.0.2. It has been declared as critical. The impacted element is an unknown function of the component ClientHello Handler. Executing a manipulation can lead to improper validation of specified quantity in input. This vulnerability is handled as CVE-2026-55952. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Erlang OTP up to 29.0.2. This vulnerability affects some unknown processing of the component ClientHello Handler. The manipulation with an unknown input leads to a improper validation of specified quantity in input vulnerability. The CWE definition for the vulnerability is CWE-1284. The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties. The impact remains unknown. CVE summarizes:

The Erlang/OTP ssl application does not validate that the PSK identity list and binder list carried in a TLS 1.3 ClientHello pre-shared key extension have equal length before passing them to the session ticket handler. In tls_handshake_1_3:handle_pre_shared_key/3, an OfferedPreSharedKeys record with a mismatched number of identities and binders is forwarded directly to tls_server_session_ticket:use/4, which crashes the session ticket handler process. An unauthenticated remote attacker can send a single crafted ClientHello to a TLS 1.3 server with session tickets enabled (stateful or stateless mode) and permanently disrupt session ticket handling on that listener. New TLS 1.3 handshakes complete but subsequently crash when the server attempts to issue a session ticket, effectively making TLS 1.3 unusable on the affected listener until the ssl application is restarted. TLS 1.2 connections are not affected. This issue affects OTP from 22.2 before 29.0.3, 28.5.0.3 and 27.3.4.14 corresponding to ssl from 9.5 before 11.7.3, 11.6.0.3 and 11.2.12.10.

The weakness was released by Lukas Backström. The advisory is shared for download at github.com. This vulnerability was named CVE-2026-55952 since 06/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available.

Upgrading to version 1.2, 1.3, 9.5, 11.2.12.10, 11.6.0.3, 11.7.3, 22.2, 27.3.4.14, 28.5.0.3 or 29.0.3 eliminates this vulnerability.

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Productinfo

Vendor

• Erlang

Name

• OTP

Version

• 1.0
• 1.1
• 1.2
• 9.0
• 9.1
• 9.2
• 9.3
• 9.4
• 11.7.0
• 11.7.1
• 11.7.2
• 22.0
• 22.1
• 29.0.0
• 29.0.1
• 29.0.2

Website

• Product: https://github.com/erlang/otp/

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