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TI-2026-40358 Aliases CVE-2026-55952

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

Priority LOW 36CWE-1284Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 1 fixed, 3 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00481 41st percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 1 fixed, 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ErlangOTP9.5 and later—No fix listedCNA
ErlangOTP22.2 and later—No fix listedCNA
  • OTP VendorErlang Affected 9.5 and later Fixed in — No fix listed CNA
  • OTP VendorErlang Affected 22.2 and later Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*22.2 to before 27.3.4.14; 28.0 to before 28.5.0.3; 29.0 to before 29.0.3VulnerableErlang
cpe:2.3:a:erlang:erlang\/ssl:*:*:*:*:*:*:*:*9.5 to before 11.2.12.10; 11.3 to before 11.6.0.3; 11.7 to before 11.7.3VulnerableErlang
  • cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* Versions 22.2 to before 27.3.4.14; 28.0 to before 28.5.0.3; 29.0 to before 29.0.3 Vulnerable ·Erlang
  • cpe:2.3:a:erlang:erlang\/ssl:*:*:*:*:*:*:*:* Versions 9.5 to before 11.2.12.10; 11.3 to before 11.6.0.3; 11.7 to before 11.7.3 Vulnerable ·Erlang

Remediation

Red Hat 1 advisory

  • RHSA-2026:63160 Released 2026-09-03 · Red Hat rating Important
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images erlang27-27.3.4.17-1.hum1@aarch64, erlang27-27.3.4.17-1.hum1@src, erlang27-27.3.4.17-1.hum1@x86_64 +47

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat OpenStack Platform 16.2AffectedNo fix yet
Red Hat OpenStack Platform 17.1AffectedNo fix yet
Red Hat OpenStack Platform 18.0AffectedNo fix yet
Red Hat Hardened ImagesFixed RHSA-2026:63160

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55952

References

  • TI-2025-23504 Erlang/OTP SSH Vulnerable to Pre-Authentication RCE KEVCVSS 3.1CRITICAL 10.0
  • TI-2023-26623 The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6… CVSS 3.1MEDIUM 5.9
  • TI-2017-14604 The Erlang otp TLS server answers with different TLS alerts to different error types in… CVSS 3.0MEDIUM 5.9
  • TI-2026-36669 Stack buffer overflow in SCTP error cause parsing in inet_drv allows remote VM crash CVSS 4.0HIGH 8.8
  • TI-2022-17230 In Erlang/OTP before 23.3.4.15, 24.x before 24.3.4.2, and 25.x before 25.0.2, there is a… CVSS 3.1CRITICAL 9.8
  • TI-2016-08327 An issue was discovered in Erlang/OTP 18.x. CVSS 3.0CRITICAL 9.8
See all 40 →

Sources