OCSP response verification in pubkey_ocsp:verify_response/5 and pubkey_ocsp:is_authorized_responder/3 in lib/public_key/src/pubkey_ocsp.erl does not check the validity period (notBefore/notAfter) of the OCSP responder certificate. An attacker who has obtained the private key of an expired CA-designated OCSP responder certificate can forge OCSP responses that Erlang/OTP accepts as valid.
This affects TLS clients using OCSP stapling via the ssl application: a malicious or compromised server can present a revoked TLS certificate together with a forged OCSP response signed by an expired responder key, and the client will accept the revoked certificate as valid. It also affects applications calling public_key:pkix_ocsp_validate/5 directly, where the impact depends on the use case — server-side client certificate validation using this API may allow authentication bypass with a revoked client certificate.
This issue affects OTP from OTP 27.0 before OTP 27.3.4.12, 28.5.0.1, and 29.0.1 corresponding to public_key from 1.16 before 1.17.1.3, 1.20.3.1, and 1.21.1.
Project Subscriptions
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Solution
No solution given by the vendor.
Workaround
* For TLS clients using the ssl application, disable OCSP stapling by setting {stapling, no_staple} in the client options, or switch to CRL-based revocation checking with {crl_check, true}. * For applications calling public_key:pkix_ocsp_validate/5 directly, validate the responder certificate's validity period in application code before calling the function.
Wed, 27 May 2026 16:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Erlang erlang/otp
Erlang otp |
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| Vendors & Products |
Erlang erlang/otp
Erlang otp |
Wed, 27 May 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
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Wed, 27 May 2026 14:15:00 +0000
| Type | Values Removed | Values Added |
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| Description | Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows forged OCSP responses signed with an expired responder certificate to be accepted as valid. OCSP response verification in pubkey_ocsp:verify_response/5 and pubkey_ocsp:is_authorized_responder/3 in lib/public_key/src/pubkey_ocsp.erl does not check the validity period (notBefore/notAfter) of the OCSP responder certificate. An attacker who has obtained the private key of an expired CA-designated OCSP responder certificate can forge OCSP responses that Erlang/OTP accepts as valid. This affects TLS clients using OCSP stapling via the ssl application: a malicious or compromised server can present a revoked TLS certificate together with a forged OCSP response signed by an expired responder key, and the client will accept the revoked certificate as valid. It also affects applications calling public_key:pkix_ocsp_validate/5 directly, where the impact depends on the use case — server-side client certificate validation using this API may allow authentication bypass with a revoked client certificate. This issue affects OTP from OTP 27.0 before OTP 27.3.4.12, 28.5.0.1, and 29.0.1 corresponding to public_key from 1.16 before 1.17.1.3, 1.20.3.1, and 1.21.1. | |
| Title | OCSP responder certificate validity period not checked in public_key | |
| First Time appeared |
Erlang
Erlang erlang\/otp |
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| Weaknesses | CWE-295 CWE-672 |
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| CPEs | cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Erlang
Erlang erlang\/otp |
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| References |
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|
| Metrics |
cvssV4_0
|
Projects
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Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-05-27T15:41:07.758Z
Reserved: 2026-04-29T18:06:33.251Z
Link: CVE-2026-42791
Updated: 2026-05-27T15:40:33.572Z
Status : Awaiting Analysis
Published: 2026-05-27T14:16:53.460
Modified: 2026-05-27T19:38:46.563
Link: CVE-2026-42791
No data.
OpenCVE Enrichment
Updated: 2026-05-27T16:30:36Z