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ALPINE-CVE-2026-42768

Type: advisorySource: OSV1 source record

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output. Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key. The attack is possible in 2 variants. 1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success. An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available. That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it. 2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted. An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle. We are not

Announced Source revision 1
Original source ↗

ALPINE-CVE-2026-42768

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:ALPINE-CVE-2026-42768

openssl

Source reference: /affected/0/package/name

Affected versions
Not stated in this record
Fixed versions
3.3.7-r1

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

openssl

Source reference: /affected/1/package/name

Affected versions
Not stated in this record
Fixed versions
3.5.7-r0

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

openssl

Source reference: /affected/2/package/name

Affected versions
Not stated in this record
Fixed versions
3.5.7-r0

Source reference: /affected/2/ranges

Prerequisites
Not stated in this record

openssl

Source reference: /affected/3/package/name

Affected versions
Not stated in this record
Fixed versions
3.5.7-r0

Source reference: /affected/3/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": "3.4.0"
          },
          {
            "fixed": "3.3.7-r1"
          }
        ]
      }
    ],
    "package": {
      "name": "openssl",
      "purl": "pkg:apk/alpine/openssl?arch=source",
      "ecosystem": "Alpine:v3.21"
    },
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-42768.json"
    },
    "ecosystem_specific": {}
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "3.4.0"
          },
          {
            "fixed": "3.5.7-r0"
          }
        ]
      }
    ],
    "package": {
      "name": "openssl",
      "purl": "pkg:apk/alpine/openssl?arch=source",
      "ecosystem": "Alpine:v3.22"
    },
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-42768.json"
    },
    "ecosystem_specific": {}
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "3.4.0"
          },
          {
            "fixed": "3.5.7-r0"
          }
        ]
      }
    ],
    "package": {
      "name": "openssl",
      "purl": "pkg:apk/alpine/openssl?arch=source",
      "ecosystem": "Alpine:v3.23"
    },
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-42768.json"
    },
    "ecosystem_specific": {}
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "3.4.0"
          },
          {
            "fixed": "3.5.7-r0"
          }
        ]
      }
    ],
    "package": {
      "name": "openssl",
      "purl": "pkg:apk/alpine/openssl?arch=source",
      "ecosystem": "Alpine:v3.24"
    },
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-42768.json"
    },
    "ecosystem_specific": {}
  }
]

Publisher severity

No explicit severity was provided.

Event
#54395 · Revision 1
Added to Heist Feed
Publisher date
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