# CVE-2011-4121: Weak cryptography in OpenSSL extension of Ruby (Git trunk)

> The Ruby OpenSSL extension generated weak RSA keys with an exponent of 1, allowing attackers to bypass integrity checks or corrupt services relying on these keys.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Nov 2019
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-mjg4-5rfj-952f

## What is CVE-2011-4121?

CVE-2011-4121 is a critical vulnerability in Ruby-Lang Ruby, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The OpenSSL extension of Ruby (Git trunk) versions after 2011-09-01 up to 2011-11-03 always generated an exponent value of '1' to be used for private RSA key generation. A remote attacker could use this flaw to bypass or corrupt integrity of services, depending on strong private RSA keys generation mechanism.

Weakness: CWE-326 (Inadequate Encryption Strength)

## Which versions are affected by CVE-2011-4121?

It affects 1 product.


Products: Ruby-Lang Ruby.

## How do I fix CVE-2011-4121?

No fix has been published for CVE-2011-4121 yet. Limit exposure of the affected software until one is available.

## Is CVE-2011-4121 being exploited?

There is no known exploitation of CVE-2011-4121 in the wild and no public exploit code.

## Other vulnerabilities in Ruby-Lang Ruby

- [CVE-2009-4124](https://insights.sbomify.com/CVE-2009-4124/): Memory corruption in n/a (critical 10.0)
- [CVE-2022-28738](https://insights.sbomify.com/CVE-2022-28738/): Use after free in n/a (critical 9.8)
- [CVE-2017-17790](https://insights.sbomify.com/CVE-2017-17790/): Command injection in n/a (critical 9.8)
- [CVE-2017-11465](https://insights.sbomify.com/CVE-2017-11465/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-2336](https://insights.sbomify.com/CVE-2016-2336/): Memory corruption in Ruby (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-4121 and fix it if it is affected.

What it is: CVE-2011-4121 is a critical vulnerability in Ruby-Lang Ruby, published on 26 Nov 2019. 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-2011-4121 in the wild and no public exploit code.

Affected product: Ruby-Lang Ruby. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2011-4121/ (Markdown: https://insights.sbomify.com/CVE-2011-4121/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-4121
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-4121
- OSV: https://osv.dev/vulnerability/CVE-2011-4121

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-4121/
Summaries are generated and may contain mistakes; the official description above is the record.