# HSEC-2023-0006: x509-validation does not enforce pathLenConstraint

> The x509-validation library fails to enforce path length constraints, allowing unauthorized intermediate CAs to issue certificates that are incorrectly accepted.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Nov 2025

## What is HSEC-2023-0006?

HSEC-2023-0006 is a vulnerability in x509-validation, published on 14 Nov 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

# x509-validation does not enforce pathLenConstraint

*x509-validation* prior to version 1.4.8 did not enforce the
pathLenConstraint value.  Constrained CAs could accidentally (or
deliberately) issue CAs below the maximum depth and
*x509-validation* would accept certificates issued by the
unauthorised intermediate CAs.

## Which versions are affected by HSEC-2023-0006?

1 open source package ship an affected version, including x509-validation.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `x509-validation` | Hackage | From 1.4.0 | 1.4.8 |

## How do I fix HSEC-2023-0006?

Upgrade x509-validation to 1.4.8 or later.

## Is HSEC-2023-0006 being exploited?

There is no known exploitation of HSEC-2023-0006 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for HSEC-2023-0006 and fix it if it is affected.

What it is: HSEC-2023-0006 is a vulnerability in x509-validation, published on 14 Nov 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of HSEC-2023-0006 in the wild and no public exploit code.

Affected packages and fixed versions:
- x509-validation (Hackage): affected from 1.4.0; fixed in 1.4.8

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/HSEC-2023-0006/ (Markdown: https://insights.sbomify.com/HSEC-2023-0006/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/HSEC-2023-0006

---
From sbomify Insights: https://insights.sbomify.com/HSEC-2023-0006/
Summaries are generated and may contain mistakes; the official description above is the record.