CVE-2026-55952: erlang\/otp — Fix

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0049

Probability of exploitation

0.39%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1284 CWE-1284

Affected Products

Vendor	Product	Versions
erlang	erlang\/otp	22.2 — 27.3.4.14
erlang	erlang\/otp	28.0 — 28.5.0.3
erlang	erlang\/otp	29.0 — 29.0.3
erlang	erlang\/ssl	9.5 — 11.2.12.10
erlang	erlang\/ssl	11.3 — 11.6.0.3
erlang	erlang\/ssl	11.7 — 11.7.3

References

Advisories & Patches

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

Other References

https://osv.dev/vulnerability/EEF-CVE-2026-55952 https://www.erlang.org/doc/system/versions.html#order-of-versions

Frequently Asked Questions

What is CVE-2026-55952? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-55952? +

CVE-2026-55952 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0049, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-55952? +

CVE-2026-55952 affects products from erlang, specifically: erlang\/otp, erlang\/ssl. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-55952? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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