CVE-2026-42791
published 2026-05-27CVE-2026-42791: Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows forged OCSP responses signed with an expired responder…
PriorityP419low3.7CVSS 3.1
AVNACHPRNUINSUCNILAN
EPSS
0.32%
23.3th percentile
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.
Affected
6 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| erlang | erlang_otp | >= 27.0 < 27.3.4.12 | 27.3.4.12 |
| erlang | erlang_otp | >= 28.0 < 28.5.0.1 | 28.5.0.1 |
| erlang | erlang_otp | >= 29.0 < 29.0.1 | 29.0.1 |
| erlang | otp | >= 1.16 < * | * |
| erlang | otp | >= 27.0 < * | * |
| erlang | otp | >= 2b1a742c651b90f8a7a1fb2ddde73f29915ea376 < * | * |
CVSS provenance
nvdv3.13.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
nvdv4.06.3MEDIUMCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vendor_redhat3.7LOW
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Bugzilla
CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation [fedora-all]
bugzilla·2026-06-23·CVSS 3.7
CVE-2026-42791 [LOW] CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation [fedora-all]
CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Bugzilla
CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation [epel-all]
bugzilla·2026-06-23·CVSS 3.7
CVE-2026-42791 [LOW] CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation [epel-all]
CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Bugzilla
CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation
bugzilla·2026-05-27·CVSS 3.7
CVE-2026-42791 [LOW] CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation
CVE-2026-42791 erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation
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
https://cna.erlef.org/cves/CVE-2026-42791.htmlhttps://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169bhttps://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fffhttps://osv.dev/vulnerability/EEF-CVE-2026-42791https://www.erlang.org/doc/system/versions.html#order-of-versions
2026-05-27
Published