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.
References
| Link | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-42791.html | Third Party Advisory |
| https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b | Patch |
| https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76 | Patch |
| https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fff | Mitigation Vendor Advisory |
| https://osv.dev/vulnerability/EEF-CVE-2026-42791 | Third Party Advisory |
| https://www.erlang.org/doc/system/versions.html#order-of-versions | Product |
Configurations
Configuration 1 (hide)
|
History
02 Jun 2026, 19:18
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://cna.erlef.org/cves/CVE-2026-42791.html - Third Party Advisory | |
| References | () https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b - Patch | |
| References | () https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76 - Patch | |
| References | () https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fff - Mitigation, Vendor Advisory | |
| References | () https://osv.dev/vulnerability/EEF-CVE-2026-42791 - Third Party Advisory | |
| References | () https://www.erlang.org/doc/system/versions.html#order-of-versions - Product | |
| CPE | cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* | |
| First Time |
Erlang
Erlang erlang\/otp |
|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 3.7 |
27 May 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-27 14:16
Updated : 2026-06-02 19:18
NVD link : CVE-2026-42791
Mitre link : CVE-2026-42791
CVE.ORG link : CVE-2026-42791
JSON object : View
Products Affected
erlang
- erlang\/otp