# CVE-2010-4237: Mercurial Improper Certificate Validation vulnerability

> Mercurial fails to verify SSL certificate Common Names, allowing attackers to perform man-in-the-middle attacks and intercept data.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/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:** 29 Oct 2019
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2010-4237, GHSA-7gf7-7wx4-mxmw, PYSEC-2026-665

## What is CVE-2010-4237?

CVE-2010-4237 is a medium-severity vulnerability in mercurial, published on 29 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Mercurial before 1.6.4 fails to verify the Common Name field of SSL certificates which allows remote attackers who acquire a certificate signed by a Certificate Authority to perform a man-in-the-middle attack.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2010-4237?

3 open source packages ship an affected version, including mercurial. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mercurial` | PyPI | All versions | 1.6.4 |
| `mercurial` | PyPI | All versions | 1.6.4 |
| `mercurial` | PyPI | All versions | 1.6.4 |

Products: Mercurial Mercurial.

## How do I fix CVE-2010-4237?

Upgrade mercurial to 1.6.4 or later.

## Is CVE-2010-4237 being exploited?

There is no known exploitation of CVE-2010-4237 in the wild and no public exploit code.

## Other vulnerabilities in mercurial

- [CVE-2018-13347](https://insights.sbomify.com/CVE-2018-13347/): Mercurial mishandles integer addition and subtraction (critical 9.8)
- [CVE-2018-17983](https://insights.sbomify.com/CVE-2018-17983/): Mercurial Out-of-bounds Read vulnerability (critical 9.1)
- [CVE-2018-13346](https://insights.sbomify.com/CVE-2018-13346/): Mercurial Improper Input Validation vulnerability (high 7.5)
- [CVE-2018-13348](https://insights.sbomify.com/CVE-2018-13348/): Mercurial Improper Input Validation vulnerability (high 7.5)
- [CVE-2014-9462](https://insights.sbomify.com/CVE-2014-9462/): Mercurial vulnerable to arbitrary command execution via a crafted repository name in a clone command (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2010-4237 and fix it if it is affected.

What it is: CVE-2010-4237 is a medium-severity vulnerability in mercurial, published on 29 Oct 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-2010-4237 in the wild and no public exploit code.

Affected packages and fixed versions:
- mercurial (PyPI): affected all versions; fixed in 1.6.4
- mercurial (PyPI): affected all versions; fixed in 1.6.4
- mercurial (PyPI): affected all versions; fixed in 1.6.4

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-2010-4237/ (Markdown: https://insights.sbomify.com/CVE-2010-4237/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2010-4237
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2010-4237
- OSV: https://osv.dev/vulnerability/CVE-2010-4237

---
From sbomify Insights: https://insights.sbomify.com/CVE-2010-4237/
Summaries are generated and may contain mistakes; the official description above is the record.