CVE-2023-2512 Buffer under-read in workerd
An integer overflow in workerd's FormData API can cause memory corruption and crashes when processing extremely large forms, requiring a runtime upgrade.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-2512?
CVE-2023-2512 is a medium-severity vulnerability in Cloudflare workerd, published on 12 May 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2023-2512?
2 open source packages ship an affected version, including workerd. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
workerd npm | All versions | 1.20230419.0 |
workerd npm | All versions | 1.20230419.0 |
Products include Cloudflare Workerd.
How do I fix CVE-2023-2512?
Upgrade workerd to 1.20230419.0 or later.
Is CVE-2023-2512 being exploited?
There is no known exploitation of CVE-2023-2512 in the wild and no public exploit code.
Sources
Also known as GHSA-8vx6-69vg-c46f.