CVE-2026-55952 - Vulnerability Details

- TLS 1.3 server denial of service via malformed ClientHello pre-shared key extension

Description

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.

Published: 2026-07-02

Score: 8.2 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The Erlang/OTP SSL application fails to check that the lists of pre‑shared key identities and binders in a TLS 1.3 ClientHello have equal length before passing the data to the session ticket handler. If the lists differ, the handler crashes, permanently disabling session ticket issuance on the listener. The crash is triggered by a single crafted ClientHello, so an unauthenticated remote attacker can cause the service to stop issuing TLS 1.3 tickets. The flaw is an input‑validation weakness identified by CWE‑1284 and CWE‑130.

Affected Systems

The vulnerability affects Erlang/OTP releases 22.2 up to, but excluding, 29.0.3, as well as 28.5.0.3 and 27.3.4.14, together with the corresponding SSL libraries 9.5 up to 11.7.3, 11.6.0.3, and 11.2.12.10. Any server running these versions with session tickets enabled is at risk.

Risk and Exploitability

The CVSS score of 8.2 indicates high severity, while the EPSS score of < 1 % shows a low but nonzero exploitation probability. The vulnerability is not listed in the CISA KEV catalog. The likely attack vector is a remote, unauthenticated attacker sending a single malformed ClientHello to a TLS 1.3 server that has session tickets enabled; the crash disables TLS 1.3 until the SSL application is restarted, while TLS 1.2 connections remain functional.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Erlang

OTP

unaffected

Version	Status	Constraints
`9.5`	affected	< *

Erlang

OTP

unaffected

Version	Status	Constraints
`22.2`	affected	< *
`339a279f02ce38a7b23010e56000613e19abb21f`	affected	< *

No data.

Vendor Product Confidence Versions

Erlang

Erlang/otp

95%

Version	Status	Scheme	Platform
`[9.5,11.2.12.10)`	affected	generic	—
`[22.2,27.3.4.14)`	affected	generic	—
`[339a279f02ce38a7b23010e56000613e19abb21f,e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce)`	affected	code_commit	—

Erlang

Otp

100%

Version	Status	Scheme	Platform
`[9.5,11.2.12.10)`	affected	generic	—

Erlang

Otp

100%

Version	Status	Scheme	Platform
`[22.2,27.3.4.14)`	affected	generic	—
`[339a279f02ce38a7b23010e56000613e19abb21f,e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce)`	affected	code_commit	—

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Remediation

Vendor Workaround

* Disable session tickets on TLS 1.3 servers by setting session_tickets to disabled in the server's ssl options. * Restrict the server to TLS 1.2 by setting versions to ['tlsv1.2'] in the server's ssl options.

OpenCVE Recommended Actions

Apply the latest Erlang/OTP release (29.0.3 or later) or the corresponding SSL library (11.7.3 or later) which removes the length‑validation bug.
If an upgrade cannot be performed immediately, disable session tickets by configuring the SSL option session_tickets to disabled so the vulnerable code path is never executed.
As a temporary measure, restrict the server to TLS 1.2 by setting the SSL option versions to ['tlsv1.2'] until the patch is deployed.

Generated by OpenCVE AI on July 21, 2026 at 11:04 UTC.

Tracking

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Advisories

No advisories yet.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00487.

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://cna.erlef.org/cves/CVE-2026-55952.html
https://github.com/erlang/otp/commit/2c3e599797644310e5d4aa39c7193420e59dadff
https://github.com/erlang/otp/commit/9b5437c72fa3403a75c1aba28e5c532bc191c662
https://github.com/erlang/otp/commit/e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce
https://github.com/erlang/otp/security/advisories/GHSA-8c57-44c9-pc59
https://nvd.nist.gov/vuln/detail/CVE-2026-55952
https://osv.dev/vulnerability/EEF-CVE-2026-55952
https://www.cve.org/CVERecord?id=CVE-2026-55952
https://www.erlang.org/doc/system/versions.html#order-of-versions

History

Fri, 03 Jul 2026 12:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-130
References		https://nvd.nist.gov/vuln/detail/CVE-2026-55952 https://www.cve.org/CVERecord?id=CVE-2026-55952
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Important`

Thu, 02 Jul 2026 18:30:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Thu, 02 Jul 2026 18:15:00 +0000

Type	Values Removed	Values Added
First Time appeared		Erlang erlang/otp Erlang otp
Vendors & Products		Erlang erlang/otp Erlang otp

Thu, 02 Jul 2026 16:45:00 +0000

Type	Values Removed	Values Added
Description		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.
Title		TLS 1.3 server denial of service via malformed ClientHello pre-shared key extension
First Time appeared		Erlang Erlang erlang\/otp
Weaknesses		CWE-1284
CPEs		cpe:2.3:a:erlang:erlang\/otp::::::::
Vendors & Products		Erlang Erlang erlang\/otp
References		https://cna.erlef.org/cves/CVE-2026-55952.html https://github.com/erlang/otp/commit/2c3e599797644310e5d4aa39c7193420e59dadff https://github.com/erlang/otp/commit/9b5437c72fa3403a75c1aba28e5c532bc191c662 https://github.com/erlang/otp/commit/e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce https://github.com/erlang/otp/security/advisories/GHSA-8c57-44c9-pc59 https://osv.dev/vulnerability/EEF-CVE-2026-55952 https://www.erlang.org/doc/system/versions.html#order-of-versions
Metrics		cvssV4_0 `{'score': 8.2, 'vector': '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'}`

Subscriptions

Erlang Erlang/otp Erlang\/otp Otp

MITRE

Status: PUBLISHED

Assigner: EEF

Published: 2026-07-02T16:06:08.474Z

Updated: 2026-07-03T04:29:07.026Z

Reserved: 2026-06-17T17:55:15.686Z

Link: CVE-2026-55952

Vulnrichment

Updated: 2026-07-02T17:28:12.551Z

NVD

No data.

Redhat

Severity : Important

Publid Date: 2026-07-02T16:06:08Z

Links: CVE-2026-55952 - Bugzilla

OpenCVE Enrichment

Updated: 2026-07-21T11:15:05Z

Weaknesses

CWE-1284
Improper Validation of Specified Quantity in Input
CWE-130
Improper Handling of Length Parameter Inconsistency

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

Exploitation none

Automatable no

Technical Impact partial

Subscriptions

JSON object

JSON object

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JSON object

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