# CVE-2023-6935: Marvin Attack vulnerability in SP Math All RSA

> Attackers can decrypt ciphertexts and forge signatures via timing attacks if static RSA is enabled, requiring configuration changes to mitigate.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Feb 2024
- **Updated:** 2 Aug 2024
- **Also known as:** DEBIAN-CVE-2023-6935, GHSA-r36f-f47x-637q, JLSEC-2026-677, UBUNTU-CVE-2023-6935

## What is CVE-2023-6935?

CVE-2023-6935 is a medium-severity vulnerability in Wolfssl Wolfssl, published on 9 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

wolfSSL SP Math All RSA implementation is vulnerable to the Marvin Attack, new variation of a timing Bleichenbacher style attack, when built with the following options to configure:

--enable-all CFLAGS="-DWOLFSSL_STATIC_RSA"

The define “WOLFSSL_STATIC_RSA” enables static RSA cipher suites, which is not recommended, and has been disabled by default since wolfSSL 3.6.6.  Therefore the default build since 3.6.6, even with "--enable-all", is not vulnerable to the Marvin Attack. The vulnerability is specific to static RSA cipher suites, and expected to be padding-independent.

The vulnerability allows an attacker to decrypt ciphertexts and forge signatures after probing with a large number of test observations. However the server’s private key is not exposed.

Weakness: CWE-203 (Observable Discrepancy)

## Which versions are affected by CVE-2023-6935?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2023-6935?

Change a configuration setting.

## Is CVE-2023-6935 being exploited?

There is no known exploitation of CVE-2023-6935 in the wild and no public exploit code.

## Other vulnerabilities in Wolfssl Wolfssl

- [CVE-2024-5991](https://insights.sbomify.com/CVE-2024-5991/): Buffer overread in domain name matching (critical 10.0)
- [CVE-2021-37155](https://insights.sbomify.com/CVE-2021-37155/): Security feature bypass in n/a (critical 9.8)
- [CVE-2020-36177](https://insights.sbomify.com/CVE-2020-36177/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2896](https://insights.sbomify.com/CVE-2014-2896/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2897](https://insights.sbomify.com/CVE-2014-2897/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-6935 and fix it if it is affected.

What it is: CVE-2023-6935 is a medium-severity vulnerability in Wolfssl Wolfssl, published on 9 Feb 2024. 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-2023-6935 in the wild and no public exploit code.

Affected product: Wolfssl Wolfssl. 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-2023-6935/ (Markdown: https://insights.sbomify.com/CVE-2023-6935/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-6935
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-6935
- OSV: https://osv.dev/vulnerability/CVE-2023-6935

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-6935/
Summaries are generated and may contain mistakes; the official description above is the record.