CVE-2024-29186

Slow String Operations via MultiPart Requests in Event-Driven Functions

An attacker could send specifically crafted requests which would force the server into performing long operations with a consequent long billed duration.

The attack has the following requirements and limitations:

• The Lambda should use the Event-Driven Function runtime.
• The Lambda should use the RequestHandlerInterface handler.
• The Lambda should implement at least an endpoint accepting POST requests.
• The attacker can send requests up to 6MB long (this is enough to cause a billed duration between 400ms and 500ms with the default 1024MB RAM Lambda image of Bref).
• If the Lambda uses a PHP runtime <= php-82 the impact is higher as the billed duration in the default 1024MB RAM Lambda image of Bref could be brought to more than 900ms for each request.

Notice that the vulnerability applies only to headers read from the request body as the request header has a limitation which allows a total maximum size of ~10KB.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2024-29186 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 (2.1.17); upgrading removes the vulnerable code path.

Kodem intelligence

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1. What is CVE-2024-29186? CVE-2024-29186 is a medium-severity uncontrolled resource consumption vulnerability in bref/bref (composer), affecting versions < 2.1.17. It is fixed in 2.1.17. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
2. How severe is CVE-2024-29186? CVE-2024-29186 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.
3. Which versions of bref/bref are affected by CVE-2024-29186? bref/bref (composer) versions < 2.1.17 is affected.
4. Is there a fix for CVE-2024-29186? Yes. CVE-2024-29186 is fixed in 2.1.17. Upgrade to this version or later.
5. Is CVE-2024-29186 exploitable, and should I be worried? Whether CVE-2024-29186 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
6. What actually determines whether CVE-2024-29186 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.
7. How do I fix CVE-2024-29186? Upgrade bref/bref to 2.1.17 or later.

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