CVE-2024-39918 is a medium-severity (CVSS 4.3) Path Traversal vulnerability in @jmondi/url-to-png. A fix is available for @jmondi/url-to-png — see the affected versions and patch details below.
Path Traveral in @jmondi/url-to-png
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-39918.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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.
@jmondi/url-to-pngnpmDescription
Summary
When trying to add a BLOCK_LIST feature when the maintainer noticed they didn't sanitize the ImageId in the code, which leads to path traversal vulnerability. Now, this is different from a traditional path traversal issue, because as of NOW you can store the image in any place arbitrarily, and given enough time they might be able to come up with a working exploit BUT for the time being they am reporting this.
Details
@jmondi/url-to-png does not sanitizing the ImageID as in not removing special chars from the params (extract_query_params.ts#l75)
const imageId = dateString + "." + slugify(validData.url) +configToString(params);
This when fed to other parts of the code such as (filesystem.ts#L34)
return path.join(this.storagePath, imageId) + ".png";
Would result in path traversal issue.
PoC
# Configuration for filesystem storage provider (optional)
STORAGE_PROVIDER=filesystem
IMAGE_STORAGE_PATH=poc
Set this in your .env file and use this as your payload.
http://localhost:3089/?url=http://example.com&width=400&isDarkMode=../../../../../../../../../../../../tmp/hack
This will create a .png file in the /tmp section of the system.
Loom POC: https://www.loom.com/share/bd7b306cdae7445c97e68f0626e743a6
This is valid for pretty much all the arguments (except for numeric values)
A simple fix would be to use the slugify for the params as well like so (#L75)
- const imageId = dateString + "." + slugify(validData.url) + configToString(params);
+ const imageId = dateString + "." + slugify(validData.url) + slugify(configToString(params));
Impact
This would be path traversal vulnerability which allows arbitrary write as of now.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @jmondi/url-to-png | all versions | 2.1.2npm install @jmondi/url-to-png@2.1.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @jmondi/url-to-png, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @jmondi/url-to-png to 2.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39918 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is CVE-2024-39918 in your dependencies?
Find it across npm, including transitive dependencies.