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DEBIAN-CVE-2026-42791

Type: advisorySource: OSV1 source record

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.

Announced Group revision 1
Original source ↗

DEBIAN-CVE-2026-42791

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:DEBIAN-CVE-2026-42791

erlang

Source reference: /affected/0/package/name

Affected versions
1:27.3.4.1+dfsg-1

Source reference: /affected/0/versions

1:27.3.4.1+dfsg-1+deb13u1

Source reference: /affected/0/versions

1:27.3.4.1+dfsg-1+deb13u2

Source reference: /affected/0/versions

Fixed versions
1:27.3.4.1+dfsg-1+deb13u3

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

erlang

Source reference: /affected/1/package/name

Affected versions
1:27.3.4.1+dfsg-1

Source reference: /affected/1/versions

1:27.3.4.10+dfsg-1

Source reference: /affected/1/versions

1:27.3.4.11+dfsg-1

Source reference: /affected/1/versions

1:27.3.4.11+dfsg-2

Source reference: /affected/1/versions

1:27.3.4.11+dfsg-3

Source reference: /affected/1/versions

1:27.3.4.11+dfsg-4

Source reference: /affected/1/versions

1:27.3.4.11+dfsg-5

Source reference: /affected/1/versions

1:27.3.4.11+dfsg-6

Source reference: /affected/1/versions

1:27.3.4.11+dfsg-7

Source reference: /affected/1/versions

1:27.3.4.3+dfsg-1

Source reference: /affected/1/versions

1:27.3.4.4+dfsg-1

Source reference: /affected/1/versions

1:27.3.4.6+dfsg-1

Source reference: /affected/1/versions

1:27.3.4.8+dfsg-1

Source reference: /affected/1/versions

1:27.3.4.9+dfsg-1

Source reference: /affected/1/versions

Fixed versions
1:27.3.4.12+dfsg-1

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "1:27.3.4.1+dfsg-1+deb13u3"
          }
        ]
      }
    ],
    "package": {
      "name": "erlang",
      "purl": "pkg:deb/debian/erlang?arch=source&distro=trixie",
      "ecosystem": "Debian:13"
    },
    "versions": [
      "1:27.3.4.1+dfsg-1",
      "1:27.3.4.1+dfsg-1+deb13u1",
      "1:27.3.4.1+dfsg-1+deb13u2"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42791.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "1:27.3.4.12+dfsg-1"
          }
        ]
      }
    ],
    "package": {
      "name": "erlang",
      "purl": "pkg:deb/debian/erlang?arch=source&distro=forky",
      "ecosystem": "Debian:14"
    },
    "versions": [
      "1:27.3.4.1+dfsg-1",
      "1:27.3.4.10+dfsg-1",
      "1:27.3.4.11+dfsg-1",
      "1:27.3.4.11+dfsg-2",
      "1:27.3.4.11+dfsg-3",
      "1:27.3.4.11+dfsg-4",
      "1:27.3.4.11+dfsg-5",
      "1:27.3.4.11+dfsg-6",
      "1:27.3.4.11+dfsg-7",
      "1:27.3.4.3+dfsg-1",
      "1:27.3.4.4+dfsg-1",
      "1:27.3.4.6+dfsg-1",
      "1:27.3.4.8+dfsg-1",
      "1:27.3.4.9+dfsg-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42791.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#56976 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement

Revision history

  1. DEBIAN-CVE-2026-42791 · Revision 1Source updated