# CVE-2023-6240: Kernel: marvin vulnerability side-channel leakage in the rsa decryption operation

> A side-channel vulnerability in the Linux Kernel RSA decryption allows attackers to decrypt ciphertexts or forge signatures, compromising private key security.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/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:** 4 Feb 2024
- **Updated:** 8 Nov 2025
- **Also known as:** BELL-CVE-2023-6240, DEBIAN-CVE-2023-6240, GHSA-5gvr-285q-pwc3, ROOT-OS-DEBIAN-11-CVE-2023-6240, ROOT-OS-DEBIAN-12-CVE-2023-6240, ROOT-OS-DEBIAN-13-CVE-2023-6240, ROOT-OS-UBUNTU-2204-CVE-2023-6240, UBUNTU-CVE-2023-6240

## What is CVE-2023-6240?

CVE-2023-6240 is a medium-severity vulnerability in Linux kernel, published on 4 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Marvin vulnerability side-channel leakage was found in the RSA decryption operation in the Linux Kernel. This issue may allow a network attacker to decrypt ciphertexts or forge signatures, limiting the services that use that private key.

Weakness: CWE-203 (Observable Discrepancy)

## Which versions are affected by CVE-2023-6240?

It affects 2 products.


Products: Linux kernel, Redhat Enterprise Linux.

## How do I fix CVE-2023-6240?

Apply the vendor's patch.

## Is CVE-2023-6240 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-6240 exists.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-6240 and fix it if it is affected.

What it is: CVE-2023-6240 is a medium-severity vulnerability in Linux kernel, published on 4 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-6240 exists.

Affected product: Linux kernel. 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-2023-6240/ (Markdown: https://insights.sbomify.com/CVE-2023-6240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-6240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-6240
- OSV: https://osv.dev/vulnerability/CVE-2023-6240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-6240/
Summaries are generated and may contain mistakes; the official description above is the record.