CVE-2026-32144: Erlang Erlang/otp

High severity, CVSS 7.4. EPSS: 0.3% chance of exploitation in the next 30 days.

Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows OCSP designated-responder authorization bypass via missing signature verification. The OCSP response validation in public_key:pkix_ocsp_validate/5 does not verify that a CA-designated responder certificate was cryptographically signed by the issuing CA. Instead, it only checks that the responder certificate's issuer name matches the CA's subject name and that the certificate has the OCSPSigning extended key usage. An attacker who can intercept or control OCSP responses can create a self-signed certificate with a matching issuer name and the OCSPSigning EKU, and use it to forge OCSP responses that mark revoked certificates as valid. This affects SSL/TLS clients using OCSP stapling, which may accept connections to servers with revoked certificates, potentially transmitting sensitive data to compromised servers. Applications using the public_key:pkix_ocsp_validate/5 API directly are also affected, with impact depending on usage context. This vulnerability is associated with program files lib/public_key/src/pubkey_ocsp.erl and program routines pubkey_ocsp:is_authorized_responder/3. This issue affects OTP from OTP 27.0 before OTP 28.4.2 and OTP 27.3.4.10, corresponding to public_key from 1.16 before 1.20.3 and 1.17.1.2, and ssl from 11.2 before 11.5.4 and 11.2.12.7.

Affected products

• Erlang Erlang/otp: from 27.0, before 27.3.4.10 (fixed in 27.3.4.10); from 28.0, before 28.4.2 (fixed in 28.4.2)
• Erlang Erlang/public Key: from 1.16, before 1.17.1.2 (fixed in 1.17.1.2); from 1.18, before 1.20.3 (fixed in 1.20.3)
• Erlang Erlang/ssl: from 11.2, before 11.2.12.7 (fixed in 11.2.12.7); after 11.3, before 11.5.4 (fixed in 11.5.4)

Published 2026-04-07. Last modified 2026-07-24.