Answer in brief
CVE-2026-42791 records a Medium severity (CVSS 6.3) vulnerability in OCSP responder certificate validity period not checked in public_key. The current sources do not mark it as known exploited. The current feed maps Erlang/erlang/otp (generic), Erlang/OTP (generic), Erlang/OTP (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Erlang/erlang/otp (generic), Erlang/OTP (generic), Erlang/OTP (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Erlang/erlang/otpgeneric | >=2b1a742c651b90f8a7a1fb2ddde73f29915ea376 <* | * |
| Erlang/OTPgeneric | >=27.0 <* | * |
| Erlang/OTPgeneric | >=1.16 <* | * |
Published upstream
May 27, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 28, 2026
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, OTP 28.5.0.1, and OTP 29.0.1, corresponding to public_key from 1.16 before 1.17.1.3, 1.20.3.1, and 1.21.1.
Quoted source text, attributed separately from HOL analysis.