CVE-2026-55952
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 OTP 22.2 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 9.5 before 11.7.3, 11.6.0.3 and 11.2.12.10.
INFO
Published Date :
July 2, 2026, 5:17 p.m.
Last Modified :
July 24, 2026, 3:18 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Affected Products
The following products are affected by CVE-2026-55952
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update Erlang/OTP to a patched version.
- Restart the ssl application.
- Verify session ticket handling.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-55952.
| URL | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-55952.html | Mitigation Vendor Advisory |
| https://github.com/erlang/otp/commit/2c3e599797644310e5d4aa39c7193420e59dadff | Patch |
| https://github.com/erlang/otp/commit/9b5437c72fa3403a75c1aba28e5c532bc191c662 | Patch |
| https://github.com/erlang/otp/commit/e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce | Patch |
| https://github.com/erlang/otp/security/advisories/GHSA-8c57-44c9-pc59 | Vendor Advisory |
| https://osv.dev/vulnerability/EEF-CVE-2026-55952 | Mitigation Third Party Advisory |
| https://www.erlang.org/doc/system/versions.html#order-of-versions | Release Notes |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55952 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-55952
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-55952 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55952 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jul. 24, 2026
Action Type Old Value New Value Changed 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. 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 OTP 22.2 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 9.5 before 11.7.3, 11.6.0.3 and 11.2.12.10. -
Initial Analysis by [email protected]
Jul. 07, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:erlang:erlang/otp:*:*:*:*:*:*:*:* versions from (including) 28.0 up to (excluding) 28.5.0.3 *cpe:2.3:a:erlang:erlang/otp:*:*:*:*:*:*:*:* versions from (including) 29.0 up to (excluding) 29.0.3 *cpe:2.3:a:erlang:erlang/otp:*:*:*:*:*:*:*:* versions from (including) 22.2 up to (excluding) 27.3.4.14 *cpe:2.3:a:erlang:erlang/ssl:*:*:*:*:*:*:*:* versions from (including) 11.3 up to (excluding) 11.6.0.3 *cpe:2.3:a:erlang:erlang/ssl:*:*:*:*:*:*:*:* versions from (including) 11.7 up to (excluding) 11.7.3 *cpe:2.3:a:erlang:erlang/ssl:*:*:*:*:*:*:*:* versions from (including) 9.5 up to (excluding) 11.2.12.10 Added Reference Type EEF: https://cna.erlef.org/cves/CVE-2026-55952.html Types: Mitigation, Vendor Advisory Added Reference Type EEF: https://github.com/erlang/otp/commit/2c3e599797644310e5d4aa39c7193420e59dadff Types: Patch Added Reference Type EEF: https://github.com/erlang/otp/commit/9b5437c72fa3403a75c1aba28e5c532bc191c662 Types: Patch Added Reference Type EEF: https://github.com/erlang/otp/commit/e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce Types: Patch Added Reference Type EEF: https://github.com/erlang/otp/security/advisories/GHSA-8c57-44c9-pc59 Types: Vendor Advisory Added Reference Type EEF: https://osv.dev/vulnerability/EEF-CVE-2026-55952 Types: Mitigation, Third Party Advisory Added Reference Type EEF: https://www.erlang.org/doc/system/versions.html#order-of-versions Types: Release Notes -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 02, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-55952', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-02T17:28:09.569991Z'} -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jul. 02, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/erlang/otp', 'vendor': 'Erlang', 'modules': ['tls_handshake_1_3'], 'product': 'OTP', 'versions': [{'status': 'affected', 'changes': [{'at': '11.7.3', 'status': 'unaffected'}, {'at': '11.6.0.3', 'status': 'unaffected'}, {'at': '11.2.12.10', 'status': 'unaffected'}], 'version': '9.5', 'lessThan': '*', 'versionType': 'otp'}], 'packageURL': 'pkg:otp/ssl?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git', 'packageName': 'ssl', 'programFiles': ['src/tls_handshake_1_3.erl'], 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'tls_handshake_1_3:handle_pre_shared_key/3'}]}, {'cpes': ['cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/erlang/otp', 'vendor': 'Erlang', 'modules': ['tls_handshake_1_3'], 'product': 'OTP', 'versions': [{'status': 'affected', 'changes': [{'at': '29.0.3', 'status': 'unaffected'}, {'at': '28.5.0.3', 'status': 'unaffected'}, {'at': '27.3.4.14', 'status': 'unaffected'}], 'version': '22.2', 'lessThan': '*', 'versionType': 'otp'}, {'status': 'affected', 'changes': [{'at': 'e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce', 'status': 'unaffected'}, {'at': '2c3e599797644310e5d4aa39c7193420e59dadff', 'status': 'unaffected'}, {'at': '9b5437c72fa3403a75c1aba28e5c532bc191c662', 'status': 'unaffected'}], 'version': '339a279f02ce38a7b23010e56000613e19abb21f', 'lessThan': '*', 'versionType': 'git'}], 'packageURL': 'pkg:github/erlang/otp', 'packageName': 'erlang/otp', 'programFiles': ['lib/ssl/src/tls_handshake_1_3.erl'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'tls_handshake_1_3:handle_pre_shared_key/3'}]}] 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. Added CVSS V4.0 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 Added CWE CWE-1284 Added Reference https://cna.erlef.org/cves/CVE-2026-55952.html Added Reference https://github.com/erlang/otp/commit/2c3e599797644310e5d4aa39c7193420e59dadff Added Reference https://github.com/erlang/otp/commit/9b5437c72fa3403a75c1aba28e5c532bc191c662 Added Reference https://github.com/erlang/otp/commit/e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce Added Reference https://github.com/erlang/otp/security/advisories/GHSA-8c57-44c9-pc59 Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-55952 Added Reference https://www.erlang.org/doc/system/versions.html#order-of-versions