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CVE Record

CVE-2019-1563: Padding Oracle in PKCS7_dataDecode and CMS_decrypt_set1_pkey

In situations where an attacker receives automated notification of the success or failure of a decryption attempt an attacker, after sending a very large number of messages to be decrypted, can recover a CMS/PKCS7 transported encryption key or decrypt any RSA encrypted message that was encrypted with the public RSA key, using a Bleichenbacher padding oracle attack. Applications are not affected if they use a certificate together with the private RSA key to the CMS_decrypt or PKCS7_decrypt functions to select the correct recipient info to decrypt. Fixed in OpenSSL 1.1.1d (Affected 1.1.1-1.1.1c). Fixed in OpenSSL 1.1.0l (Affected 1.1.0-1.1.0k). Fixed in OpenSSL 1.0.2t (Affected 1.0.2-1.0.2s).

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This OpenSSL flaw can turn decryption success or failure messages into a signal that helps recover protected content. It matters most for services that automatically decrypt CMS/PKCS7 or RSA-encrypted input and reveal whether decryption worked. The sources do not show active exploitation.

Executive priority

Treat this as a targeted crypto-library remediation item, not a broad emergency. Prioritize internet-facing or partner-facing systems that automatically decrypt encrypted messages and leak success or failure. Routine fleet patching should still close the issue because OpenSSL is widely embedded.

Technical view

CVE-2019-1563 is a Bleichenbacher-style padding oracle in OpenSSL PKCS7_dataDecode and CMS_decrypt_set1_pkey. Affected ranges are OpenSSL 1.1.1 through 1.1.1c, 1.1.0 through 1.1.0k, and 1.0.2 through 1.0.2s. OpenSSL fixed it in 1.1.1d, 1.1.0l, and 1.0.2t.

Likely exposure

Exposure is most likely in custom applications, mail/security gateways, or automation that accepts attacker-controlled encrypted CMS/PKCS7 or RSA messages and returns distinguishable decryption success or failure notifications. Applications using a certificate with the private key to select the recipient info are described as not affected.

Exploitation context

Successful abuse requires many decryption attempts and an observable success/failure oracle. The provided bundle has no KEV listing and no cited evidence of active exploitation. Risk increases when automated decryption is reachable by untrusted users.

Researcher notes

The critical condition is oracle visibility, not merely having OpenSSL installed. Focus validation on reachable decryption workflows, API usage, linked library versions, and whether responses differ on padding or recipient failures. The source description explicitly narrows non-affected CMS_decrypt and PKCS7_decrypt usage when a certificate accompanies the private key.

Mitigation direction

  • Upgrade OpenSSL to 1.1.1d, 1.1.0l, 1.0.2t, or vendor-patched packages.
  • Apply distribution advisories from Debian, Fedora, openSUSE, Ubuntu, Slackware, Gentoo, or Oracle as applicable.
  • Inventory applications using PKCS7_decrypt, CMS_decrypt, PKCS7_dataDecode, or CMS_decrypt_set1_pkey.
  • Review vendor guidance for packaged products embedding OpenSSL.
  • Avoid exposing distinguishable automated decryption success or failure responses to untrusted callers.

Validation and detection

  • Confirm OpenSSL runtime and linked library versions on affected hosts and containers.
  • Check package manager advisories for the fixed distribution build, not only upstream version strings.
  • Identify services that decrypt CMS/PKCS7 or RSA-encrypted messages automatically.
  • Verify applications use certificate-plus-private-key recipient selection where relevant.
  • Review logs for unusually high volumes of failed decryption attempts.
Prepared
Confidence
high
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
26Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
OpenSSLOpenSSLFixed in OpenSSL 1.1.1d (Affected 1.1.1-1.1.1c), Fixed in OpenSSL 1.1.0l (Affected 1.1.0-1.1.0k), Fixed in OpenSSL 1.0.2t (Affected 1.0.2-1.0.2s)Listed
Weakness

CWE details

No CWE listed

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