smol-toml: Denial of Service via TOML documents containing thousands of consecutive commented linesGHSA-v3rj-xjv7-4jmq
MEDIUMGHSA-v3rj-xjv7-4jmq is a medium-severity (CVSS 5.3) remote code execution vulnerability in smol-toml. A fix is available for smol-toml — see the affected versions and patch details below.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
smol-tomlnpmDescription
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
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | smol-toml | all versions | 1.6.1npm install smol-toml@1.6.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for smol-toml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update smol-toml to 1.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-v3rj-xjv7-4jmq is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Frequently Asked Questions
Is GHSA-v3rj-xjv7-4jmq in your dependencies?
Find it across npm, including transitive dependencies.