Summary
@jmondi/url-to-png contains a Path Traversal vulnerability
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.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2024-39918 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.1.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2024-39918? CVE-2024-39918 is a medium-severity path traversal vulnerability in @jmondi/url-to-png (npm), affecting versions < 2.1.2. It is fixed in 2.1.2. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2024-39918? CVE-2024-39918 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of @jmondi/url-to-png are affected by CVE-2024-39918? @jmondi/url-to-png (npm) versions < 2.1.2 is affected.
- Is there a fix for CVE-2024-39918? Yes. CVE-2024-39918 is fixed in 2.1.2. Upgrade to this version or later.
- Is CVE-2024-39918 exploitable, and should I be worried? Whether CVE-2024-39918 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2024-39918 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2024-39918? Upgrade
@jmondi/url-to-pngto 2.1.2 or later.