CVE-2007-6721 Legion of the Bouncy Castle Java Cryptography API Bleichenbacher Oracle Vulnerability

What is CVE-2007-6721?

CVE-2007-6721 is a critical vulnerability in Bouncycastle Bc-Java, published on 30 Mar 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The Legion of the Bouncy Castle Java Cryptography API before release 1.38, as used in Crypto Provider Package before 1.36, has unknown impact and remote attack vectors related to "a Bleichenbacher vulnerability in simple RSA CMS signatures without signed attributes."

Which versions are affected by CVE-2007-6721?

6 open source packages ship an affected version, including bouncycastle:bcprov-jdk14, bouncycastle:bcprov-jdk15 and bouncycastle:bcprov-jdk16. It affects 2 products.

Products include Bouncycastle Bc-Java, Bouncycastle Bouncy-Castle-Crypto-Package.

How do I fix CVE-2007-6721?

Upgrade bouncycastle:bcprov-jdk14 to 1.38 or later.

Is CVE-2007-6721 being exploited?

There is no known exploitation of CVE-2007-6721 in the wild and no public exploit code.

Other vulnerabilities in Bouncycastle Bc-Java

• CVE-2018-1000613 Deserialization of Untrusted Data in Bouncy castle Critical 9.8
• CVE-2026-58062 Stapled OCSP response accepted without binding to the checked certificate Critical 9.3
• CVE-2026-59638 JSSE hostname verifier CN-fallback enabled by default despite documented opt-in Critical 9.3
• CVE-2026-59650 MTI/A0 DH agreement exponentiates unvalidated peer value Critical 9.3
• CVE-2026-8763 Name Constraints bypass via trailing dot in rfc822Name and URI Critical 9.3

All Bouncycastle Bc-Java vulnerabilities

Sources

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

Also known as DEBIAN-CVE-2007-6721, GHSA-m26p-m559-g5j5.