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

> A Bleichenbacher vulnerability in RSA CMS signatures allows attackers to bypass cryptographic verification in the Bouncy Castle Java library.

- **Severity:** Critical 10.0 (`AV:N/AC:L/Au:N/C:C/I:C/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Mar 2009
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2007-6721, GHSA-m26p-m559-g5j5

## 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.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bouncycastle:bcprov-jdk14` | Maven | All versions | 1.38 |
| `bouncycastle:bcprov-jdk14` | Maven | All versions | 1.38 |
| `bouncycastle:bcprov-jdk15` | Maven | All versions | 1.38 |
| `bouncycastle:bcprov-jdk15` | Maven | All versions | 1.38 |
| `bouncycastle:bcprov-jdk16` | Maven | All versions | 1.38 |
| `bouncycastle:bcprov-jdk16` | Maven | All versions | 1.38 |

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

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2007-6721 and fix it if it is affected.

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

Affected packages and fixed versions:
- bouncycastle:bcprov-jdk14 (Maven): affected all versions; fixed in 1.38
- bouncycastle:bcprov-jdk14 (Maven): affected all versions; fixed in 1.38
- bouncycastle:bcprov-jdk15 (Maven): affected all versions; fixed in 1.38
- bouncycastle:bcprov-jdk15 (Maven): affected all versions; fixed in 1.38
- bouncycastle:bcprov-jdk16 (Maven): affected all versions; fixed in 1.38
- bouncycastle:bcprov-jdk16 (Maven): affected all versions; fixed in 1.38

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2007-6721/ (Markdown: https://insights.sbomify.com/CVE-2007-6721/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2007-6721
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2007-6721
- OSV: https://osv.dev/vulnerability/CVE-2007-6721

---
From sbomify Insights: https://insights.sbomify.com/CVE-2007-6721/
Summaries are generated and may contain mistakes; the official description above is the record.