# CVE-2023-50781: M2crypto: bleichenbacher timing attacks in the rsa decryption api - incomplete fix for cve-2020-25657

> A remote attacker can decrypt captured TLS messages using RSA key exchanges via timing attacks, exposing sensitive data.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/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:** 5 Feb 2024
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-101841, DEBIAN-CVE-2023-50781, GHSA-944j-8ch6-rf6x, PYSEC-2026-1595, UBUNTU-CVE-2023-50781

## What is CVE-2023-50781?

CVE-2023-50781 is a high-severity vulnerability in Redhat Enterprise Linux, published on 5 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in m2crypto. This issue may allow a remote attacker to decrypt captured messages in TLS servers that use RSA key exchanges, which may lead to exposure of confidential or sensitive data.

Weakness: CWE-203 (Observable Discrepancy)

## Which versions are affected by CVE-2023-50781?

3 open source packages ship an affected version, including m2crypto. It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `m2crypto` | PyPI | All versions to 0.40.1 | None |
| `m2crypto` | PyPI | All versions to 0.40.1 | None |
| `m2crypto` | PyPI | All versions to 0.40.1 | None |

Products: M2crypto Project M2crypto, Redhat Enterprise Linux, Redhat Update Infrastructure.

## How do I fix CVE-2023-50781?

Apply the vendor's patch.

## Is CVE-2023-50781 being exploited?

There is no known exploitation of CVE-2023-50781 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-50781 and fix it if it is affected.

What it is: CVE-2023-50781 is a high-severity vulnerability in Redhat Enterprise Linux, published on 5 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-2023-50781 in the wild and no public exploit code.

Affected packages and fixed versions:
- m2crypto (PyPI): affected all versions up to 0.40.1; no fix listed
- m2crypto (PyPI): affected all versions up to 0.40.1; no fix listed
- m2crypto (PyPI): affected all versions up to 0.40.1; no fix listed

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-2023-50781/ (Markdown: https://insights.sbomify.com/CVE-2023-50781/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-50781
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-50781
- OSV: https://osv.dev/vulnerability/CVE-2023-50781

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-50781/
Summaries are generated and may contain mistakes; the official description above is the record.