Improper Certificate Validation Affecting erlang27 package, versions <0:27.3.4.17-1.hum1


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.32% (25th percentile)

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  • Snyk IDSNYK-RHEL10-ERLANG27-19893283
  • published18 Sept 2026
  • disclosed27 May 2026

Introduced: 27 May 2026

CVE-2026-42791  (opens in a new tab)
CWE-295  (opens in a new tab)

How to fix?

Upgrade RHEL:10 erlang27 to version 0:27.3.4.17-1.hum1 or higher.
This issue was patched in RHSA-2026:63160.

NVD Description

Note: Versions mentioned in the description apply only to the upstream erlang27 package and not the erlang27 package as distributed by RHEL. See How to fix? for RHEL:10 relevant fixed versions and status.

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 29.0.1, OTP 28.5.0.1 and OTP 27.3.4.12, corresponding to public_key from 1.16 before 1.21.1, 1.20.3.1 and 1.17.1.3.

CVSS Base Scores

version 3.1