High severity · published Jul 2, 2026
CVE-2026-55952
TLS 1.3 server denial of service via malformed ClientHello pre-shared key extension
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 41% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OT
OTP · Erlang
9.5; 22.2; 339a279f02ce38a7b23010e56000613e19abb21f · source: vendor
ER
Erlang/otp · Erlang
22.2 before 27.3.4.14; 28.0 before 28.5.0.3; 29.0 before 29.0.3 · source: NVD
ER
Erlang/ssl · Erlang
9.5 before 11.2.12.10; 11.3 before 11.6.0.3; 11.7 before 11.7.3 · source: NVD
Affected product
OT
OTP
Erlang
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