What is CVE-2025-24033?

CVE-2025-24033 is a high-severity allocation of resources without limits or throttling vulnerability in @fastify/multipart (npm), affecting versions <= 8.3.0. It is fixed in 8.3.1, 9.0.3. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.

How severe is CVE-2025-24033?

CVE-2025-24033 has a CVSS score of 7.5 (High). 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 @fastify/multipart are affected by CVE-2025-24033?

@fastify/multipart (npm) versions <= 8.3.0 is affected.

Is there a fix for CVE-2025-24033?

Yes. CVE-2025-24033 is fixed in 8.3.1, 9.0.3. Upgrade to this version or later.

Is CVE-2025-24033 exploitable, and should I be worried?

Whether CVE-2025-24033 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.

What actually determines whether CVE-2025-24033 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.

CVE-2025-24033 in @fastify/multipart

Q: How severe is CVE-2025-24033?

CVE-2025-24033 has a CVSS score of 7.5 (High). 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.

Q: Which versions of @fastify/multipart are affected by CVE-2025-24033?

@fastify/multipart (npm) versions <= 8.3.0 is affected.

Q: Is there a fix for CVE-2025-24033?

Yes. CVE-2025-24033 is fixed in 8.3.1, 9.0.3. Upgrade to this version or later.

Q: Is CVE-2025-24033 exploitable, and should I be worried?

Whether CVE-2025-24033 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.

Q: What actually determines whether CVE-2025-24033 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.

Q: How do I fix CVE-2025-24033?

Upgrade: @fastify/multipart to 8.3.1 or later, @fastify/multipart to 9.0.3 or later.

Summary

Unlimited consumption of resources in @fastify/multipart

Fixed in version 8.3.1 and 9.0.3

Workarounds

Do not use saveRequestFiles.

References

This was identified in https://github.com/fastify/fastify-multipart/issues/546 and fixed in https://github.com/fastify/fastify-multipart/pull/567.

Impact

The saveRequestFiles function does not delete the uploaded temporary files when user cancels the request.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2025-24033 has a CVSS score of 7.5 (High). 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 (8.3.1, 9.0.3); upgrading removes the vulnerable code path.

Affected versions

@fastify/multipart (<= 8.3.0) @fastify/multipart (>= 9.0.0, < 9.0.3)

Security releases

@fastify/multipart → 8.3.1 (npm) @fastify/multipart → 9.0.3 (npm)

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.

Already deployed Kodem?

See it in your environment New to Kodem? Get a demo →

Remediation advice

Upgrade the following packages to resolve this vulnerability:

@fastify/multipart to 8.3.1 or later; @fastify/multipart to 9.0.3 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2025-24033? CVE-2025-24033 is a high-severity allocation of resources without limits or throttling vulnerability in @fastify/multipart (npm), affecting versions <= 8.3.0. It is fixed in 8.3.1, 9.0.3. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
How severe is CVE-2025-24033? CVE-2025-24033 has a CVSS score of 7.5 (High). 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 @fastify/multipart are affected by CVE-2025-24033? @fastify/multipart (npm) versions <= 8.3.0 is affected.
Is there a fix for CVE-2025-24033? Yes. CVE-2025-24033 is fixed in 8.3.1, 9.0.3. Upgrade to this version or later.
Is CVE-2025-24033 exploitable, and should I be worried? Whether CVE-2025-24033 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-2025-24033 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-2025-24033?
- Upgrade @fastify/multipart to 8.3.1 or later
- Upgrade @fastify/multipart to 9.0.3 or later

Other vulnerabilities in @fastify/multipart

CVE-IDSeverityPackage summary

CVE-2023-25576High@fastify/multipart: Denial of service due to unlimited number of parts