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Erlang/OTP CVE-2026-55952

| EUVDEUVD-2026-41412 HIGH
Improper Validation of Specified Quantity in Input (CWE-1284)
2026-07-02 EEF
Denial Of Service Otp Red Hat Suse
8.2
CVSS 4.0 · Vendor: EEF
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Severity by source

Vendor (EEF) PRIMARY
8.2 HIGH
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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
7.5 HIGH

Single unauthenticated network ClientHello triggers it (AV:N/AC:L/PR:N/UI:N); impact is availability-only DoS of TLS 1.3 tickets, so C:N/I:N/A:H and scope unchanged.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (EEF).

CVSS VectorVendor: EEF

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

1
Analysis Generated
Jul 02, 2026 - 17:21 vuln.today

DescriptionCVE.org

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.

AnalysisAI

Denial of service in the Erlang/OTP ssl application (OTP 22.2 through 29.0.3, and the 28.5.x/27.3.x maintenance branches) lets an unauthenticated remote attacker permanently disable TLS 1.3 session ticket handling on a listener with a single crafted ClientHello. Because the pre-shared key extension's identity list and binder list are not length-checked before being handed to the session ticket handler, a mismatched OfferedPreSharedKeys record crashes that process, causing all subsequent TLS 1.3 handshakes to fail at ticket issuance until the ssl application is restarted. No public exploit identified at time of analysis and it is not on CISA KEV, but the CVSS 4.0 base score of 8.2 reflects the trivial, pre-authentication trigger.

Technical ContextAI

The affected component is the ssl application shipped with Erlang/OTP, which provides the native TLS/DTLS stack used by Erlang and Elixir services (for example web servers built on Cowboy/Phoenix and message brokers such as RabbitMQ). The flaw lives in the TLS 1.3 handshake state machine: tls_handshake_1_3:handle_pre_shared_key/3 receives an OfferedPreSharedKeys record parsed from the ClientHello pre-shared key (PSK) extension. RFC 8446 requires the extension's identity list and binder list to have the same number of entries, but the code forwards the record straight to tls_server_session_ticket:use/4 without validating that the two lists are equal length. The mismatch produces an unhandled condition that crashes the session ticket handler process. The root cause maps to CWE-1284 (Improper Validation of Specified Quantity in Input) - the quantity relationship between two parallel lists is never enforced. Affected products per CPE are cpe:2.3:a:erlang:otp with the fix landing in ssl 11.7.3, 11.6.0.3 and 11.2.12.10.

RemediationAI

Upgrade Erlang/OTP to a fixed release: Vendor-released patch: OTP 29.0.3 (ssl 11.7.3), or on the maintenance branches OTP 28.5.0.3 (ssl 11.6.0.3) or 27.3.4.14 (ssl 11.2.12.10); choose the fixed version on your current major line to minimize disruption. The fixes are in commits e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce, 2c3e599797644310e5d4aa39c7193420e59dadff and 9b5437c72fa3403a75c1aba28e5c532bc191c662, per advisory GHSA-8c57-44c9-pc59 (https://github.com/erlang/otp/security/advisories/GHSA-8c57-44c9-pc59). If you cannot patch immediately, disable TLS 1.3 session tickets on the listener (for example remove stateful/stateless anti-replay/session ticket options in the ssl listener configuration) so the vulnerable code path in tls_server_session_ticket:use/4 is not reached - the trade-off is loss of TLS 1.3 session resumption, adding full-handshake overhead for returning clients. Alternatively, constraining the listener to TLS 1.2 avoids the flaw entirely but sacrifices TLS 1.3 (and 0-RTT/1.3 performance and forward-looking cipher support). As an operational stopgap, monitor the ssl application supervisor and auto-restart on the session ticket handler crash to restore TLS 1.3, and place the endpoint behind a TLS-terminating proxy that is not affected.

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
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

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CVE-2026-55952 vulnerability details – vuln.today
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