CVE-2023-2512: Buffer under-read in workerd
Impact Prior to version v1.20230419.0, the FormData API implementation was subject to an integer overflow. If a FormData instance contained more than 2^31 elements, the forEach() method could end up reading from the wrong location in memory while iterating over elements. This would most likely lead to a segmentation fault, but could theoretically allow arbitrary undefined behavior.
In order for the bug to be exploitable, the process would need to be able to allocate 160GB of RAM. Due to this, the bug was never exploitable on the Cloudflare Workers platform, but could theoretically be exploitable on deployments of workerd running on machines with a huge amount of memory. Moreover, in order to be remotely exploited, an attacker would have to upload a single form-encoded HTTP request of at least tens of gigabytes in size. The application code would then have to use request.formData() to parse the request and formData.forEach() to iterate over this data. Due to these limitations, the exploitation likelihood was considered Low.
Patches A fix that addresses this vulnerability has been released in version v1.20230419.0 and users are encouraged to update to the latest version available.
References Release - https://github.com/cloudflare/workerd/releases/tag/v1.20230419.0
Other sources
Prior to version v1.20230419.0, the FormData API implementation was subject to an integer overflow. If a FormData instance contained more than 2^31 elements, the forEach() method could end up reading from the wrong location in memory while iterating over elements. This would most likely lead to a segmentation fault, but could theoretically allow arbitrary undefined behavior.
In order for the bug to be exploitable, the process would need to be able to allocate 160GB of RAM. Due to this, the bug was never exploitable on the Cloudflare Workers platform, but could theoretically be exploitable on deployments of workerd running on machines with a huge amount of memory. Moreover, in order to be remotely exploited, an attacker would have to upload a single form-encoded HTTP request of at least tens of gigabytes in size. The application code would then have to use request.formData() to parse the request and formData.forEach() to iterate over this data. Due to these limitations, the exploitation likelihood was considered Low.
A fix that addresses this vulnerability has been released in version v1.20230419.0 and users are encouraged to update to the latest version available.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the impact of CVE-2023-2512?
The impact of CVE-2023-2512 is an integer overflow in the FormData API implementation, which could result in memory corruption and potential security vulnerabilities.
How can CVE-2023-2512 be exploited?
CVE-2023-2512 can be exploited by creating a FormData instance with more than 2^31 elements and then using the `forEach()` method, which may lead to reading from the wrong memory location.
What is the severity of CVE-2023-2512?
CVE-2023-2512 has a severity rating of 8.1 (high) based on the Common Vulnerability Scoring System (CVSS) version 3.0.
How do I fix CVE-2023-2512?
To fix CVE-2023-2512, it is recommended to update to version v1.20230419.0 or later of the affected software.
Which software versions are affected by CVE-2023-2512?
Versions prior to v1.20230419.0 of the FormData API implementation are affected by CVE-2023-2512.