CVE-2020-26939 Observable Differences in Behavior to Error Inputs in Bouncy Castle

What is CVE-2020-26939?

CVE-2020-26939 is a medium-severity vulnerability in n/a, published on 2 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-203

Which versions are affected by CVE-2020-26939?

16 open source packages ship an affected version, including org.bouncycastle:bc-fips, org.bouncycastle:bcprov-ext-jdk15on and org.bouncycastle:bcprov-ext-jdk16. It affects 2 products.

Products include Bouncycastle Fips Java Api, Bouncycastle Legion-of-the-Bouncy-Castle.

How do I fix CVE-2020-26939?

Upgrade org.bouncycastle:bc-fips to 1.0.2 or later.

Is CVE-2020-26939 being exploited?

There is no known exploitation of CVE-2020-26939 in the wild and no public exploit code.

Other vulnerabilities in n/a

• CVE-2022-45146 Garbage collection issue in BC-FJA in Java 13 and later Medium 5.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2020-26939, DLA-2433-1, GHSA-72m5-fvvv-55m6, UBUNTU-CVE-2020-26939.