What’s Vulnerable › Vulnerabilities

CVE-2020-26939

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-11-02 · updated 2026-06-17
• Weakness: CWE-203

Description

In Legion of the Bouncy Castle BC before 1.61 and BC-FJA before 1.0.1.2, attackers can obtain sensitive information about a private exponent because of Observable Differences in Behavior to Error Inputs. This occurs in org.bouncycastle.crypto.encodings.OAEPEncoding. Sending invalid ciphertext that decrypts to a short payload in the OAEP Decoder could result in the throwing of an early exception, potentially leaking some information about the private exponent of the RSA private key performing the encryption.

Affected products

• Bouncycastle Fips Java Api: before 1.0.1.2 — fixed in 1.0.1.2
• Bouncycastle Legion-Of-The-Bouncy-Castle: before 1.61 — fixed in 1.61

How to fix

Upgrade to a fixed version: Bouncycastle Fips Java Api 1.0.1.2; Bouncycastle Legion-Of-The-Bouncy-Castle 1.61. Check the vendor advisory for mitigations.

References

• https://github.com/bcgit/bc-java/wiki/CVE-2020-26939
• https://lists.apache.org/thread.html/r8c36ba34e80e05eecb1f80071cc834d705616f315b634ec0c7d8f42e%40%3Cissues.solr.apache.org%3E
• https://github.com/bcgit/bc-java/wiki/CVE-2020-26939
• https://lists.apache.org/thread.html/r8c36ba34e80e05eecb1f80071cc834d705616f315b634ec0c7d8f42e%40%3Cissues.solr.apache.org%3E

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