Is CVE-2026-55953 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-55953 being exploited in the wild.

How severe is CVE-2026-55953?

Informational severity, with a CVSS score of 9.1, published 27 July 2026.

Which products and versions are affected?

Erlang OTP 17.0 to 27.3.4.14, 28.0 to 28.5.0.3, 29.0 to 29.0.3; Erlang ssl 5.3.4 to 11.2.12.10, 11.6.0.0 to 11.6.0.3, 11.7.0 to 11.7.3.

Is there a fix for CVE-2026-55953?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-55953 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-55953?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-55953: Erlang OTP authentication bypass in SSL TLS 1.2 client

CVE-2026-55953 · Severity: info · CVSS 9.1 · Published 2026-07-27

A security flaw in the Erlang/OTP SSL library allows an attacker positioned between a client and server to intercept and modify encrypted communications. By forcing the client to use an 'anonymous' encryption method that was never requested, the attacker can bypass identity checks and certificate validation. This allows the attacker to read sensitive data or inject malicious content into what should be a secure connection.

Quick answers

Is CVE-2026-55953 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-55953 being exploited in the wild.
How severe is CVE-2026-55953?: Informational severity, with a CVSS score of 9.1, published 27 July 2026.
Which products and versions are affected?: Erlang OTP 17.0 to 27.3.4.14, 28.0 to 28.5.0.3, 29.0 to 29.0.3; Erlang ssl 5.3.4 to 11.2.12.10, 11.6.0.0 to 11.6.0.3, 11.7.0 to 11.7.3.
Is there a fix for CVE-2026-55953?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-55953 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-55953?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in the Erlang/OTP ssl application where the TLS 1.2 (and earlier) and DTLS client-side handshake handler (tls_handshake:hello/5) fails to perform a membership check on the cipher suite returned by the server. An on-path attacker can respond with a ServerHello selecting an anonymous key exchange suite (e.g., TLS_DH_anon_*) that the client did not offer. Because anonymous suites do not require a server certificate, the client's verify_peer and cacerts configurations are bypassed, resulting in a successful handshake with the attacker. This allows for complete Adversary-in-the-Middle (AiTM) capabilities, including reading and modifying application traffic. The issue is fixed in OTP versions 29.0.4, 28.5.0.4, and 27.3.4.15.

Affected products

Erlang OTP 17.0 to 27.3.4.14, 28.0 to 28.5.0.3, 29.0 to 29.0.3
Erlang ssl 5.3.4 to 11.2.12.10, 11.6.0.0 to 11.6.0.3, 11.7.0 to 11.7.3

Timeline

2026-07-27: advisory
2026-07-27: disclosed

References

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