TLS 1.3 server denial of service via malformed ClientHello pre-shared key extension
Summary
| CVE | CVE-2026-55952 |
|---|---|
| State | PUBLISHED |
| Assigner | EEF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-02 17:17:03 UTC |
| Updated | 2026-07-07 14:44:47 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 8.2 HIGH from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
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
EPSS: 0.004640000 probability, percentile 0.369450000 (date 2026-07-05)
Problem Types: CWE-1284 | CWE-1284 CWE-1284 Improper Validation of Specified Quantity in Input
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | Secondary | 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/C... |
| 4.0 | CNA | CVSS | 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 |
| 3.1 | [email protected] | Primary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v4.0 Breakdown
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
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Erlang | Erlang/otp | All | All | All | All |
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/erlang/otp/commit/9b5437c72fa3403a75c1aba28e5c532bc191c662 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Patch |
| www.erlang.org/doc/system/versions.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | www.erlang.org | Release Notes |
| osv.dev/vulnerability/EEF-CVE-2026-55952 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | osv.dev | Mitigation, Third Party Advisory |
| cna.erlef.org/cves/CVE-2026-55952.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | cna.erlef.org | Mitigation, Vendor Advisory |
| github.com/erlang/otp/commit/2c3e599797644310e5d4aa39c7193420e59dadff | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Patch |
| github.com/erlang/otp/security/advisories/GHSA-8c57-44c9-pc59 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Vendor Advisory |
| github.com/erlang/otp/commit/e77823e6d980b2ec0b4fe4ea3f2d098ca239e3ce | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Patch |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Lukas Backström (en)
CNA: Ingela Anderton Andin (en)
CNA: Dan Gudmundsson (en)
CNA: Jakub Witczak (en)
Additional Advisory Data
Workarounds
CNA: * 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.