# GHSA-v3rj-xjv7-4jmq: smol-toml: Denial of Service via TOML documents containing thousands of consecutive commented lines

> An attacker can crash applications parsing untrusted TOML by sending documents with thousands of consecutive comments, causing a stack overflow.

- **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:** 25 Mar 2026

## What is GHSA-v3rj-xjv7-4jmq?

GHSA-v3rj-xjv7-4jmq is a denial of service vulnerability in smol-toml, published on 25 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

### Summary
An attacker can send a maliciously crafted TOML to cause the parser to crash, because of a stack overflow caused by thousands of consecutive commented lines.

The library uses recursion internally while parsing to skip over commented lines, which can be exploited to crash an application that is processing arbitrary TOML documents.

### Proof of concept
```js
require("smol-toml").parse('# comment\n'.repeat(8000) + 'key = "value"')
```

### Impact
Applications which parse arbitrary TOML documents may suffer availability issues if they receive malicious input. If uncaught, the crash may cause the application itself to crash. The impact is deemed minor, as the function is already likely to throw errors on invalid input. Downstream users are supposed to properly handle errors in such situations.

Due to the design of most JavaScript runtimes, the uncontrolled recursion does not lead to excessive memory usage and the execution is quickly aborted.

As a reminder, it is **strongly** advised when working with untrusted user input to expect errors to occur and to appropriately catch them.

### Patches
Version 1.6.1 uses a different approach for parsing comments, which no longer involves recursion.

### Workarounds
Wrap all invocations of `parse` and `stringify` in a try/catch block when dealing with untrusted user input.

## Which versions are affected by GHSA-v3rj-xjv7-4jmq?

2 open source packages ship an affected version, including smol-toml.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `smol-toml` | npm | All versions | 1.6.1 |
| `smol-toml` | npm | All versions | 1.6.1 |

## How do I fix GHSA-v3rj-xjv7-4jmq?

Upgrade smol-toml to 1.6.1 or later.

## Is GHSA-v3rj-xjv7-4jmq being exploited?

There is no known exploitation of GHSA-v3rj-xjv7-4jmq in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-v3rj-xjv7-4jmq and fix it if it is affected.

What it is: GHSA-v3rj-xjv7-4jmq is a denial of service vulnerability in smol-toml, published on 25 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-v3rj-xjv7-4jmq in the wild and no public exploit code.

Affected packages and fixed versions:
- smol-toml (npm): affected all versions; fixed in 1.6.1
- smol-toml (npm): affected all versions; fixed in 1.6.1

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/GHSA-v3rj-xjv7-4jmq/ (Markdown: https://insights.sbomify.com/GHSA-v3rj-xjv7-4jmq/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-v3rj-xjv7-4jmq

---
From sbomify Insights: https://insights.sbomify.com/GHSA-v3rj-xjv7-4jmq/
Summaries are generated and may contain mistakes; the official description above is the record.