Summary
Buffer overflow in deprecated USB HALs and stack overflow in USB enumeration
Removal of deprecated HALs
Deprecated usb kit HALs have been removed in v3.2.3.
Workarounds
This vulnerability is limited to users of the kit protocol which is used with Microchip kits and kit firmware to bridge communication from USB-HID to I2C or SWI. It is not expected that kits would be used in an production environment. This is an optional component for users as well so they can always compile the library without the usb support option.
Special python packaging notes
The python package for cryptoauthlib uses date codes for identifying versions. The patched version for python packages is 20200912
References
Please see Microchip PSIRT for Microchip's security policy and reporting procedures
Credits
Special thanks to Ruben Santamarta of IOActive for reporting
Impact
If an application is making use of the deprecated kit protocol HALs as the communication channel to the target device an attacker can masquerade as a device and return malformed packets of arbitrary length which the protocol stack will write to the stack. HALs intended for production use are unaffected (I2C, SWI, & SPI) as well as the hidapi HAL (hal_all_platforms_kit_hidapi.c).
The hidapi HAL can be made to overrun the application stack by attaching more than 10 (real or virtual) devices likely resulting in an application crash as this does not allow arbitrary data to be written to the stack.
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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USB kit enumeration has been patched in v3.2.3 for the hidapi HAL (hal_all_platforms_kit_hidapi.c).
Frequently Asked Questions
- What is GHSA-F366-4RVV-95X2? GHSA-F366-4RVV-95X2 is a low-severity security vulnerability in cryptoauthlib (pip), affecting versions < 20200912. It is fixed in 20200912.
- Which versions of cryptoauthlib are affected by GHSA-F366-4RVV-95X2? cryptoauthlib (pip) versions < 20200912 is affected.
- Is there a fix for GHSA-F366-4RVV-95X2? Yes. GHSA-F366-4RVV-95X2 is fixed in 20200912. Upgrade to this version or later.
- Is GHSA-F366-4RVV-95X2 exploitable, and should I be worried? Whether GHSA-F366-4RVV-95X2 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 GHSA-F366-4RVV-95X2 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 GHSA-F366-4RVV-95X2? Upgrade
cryptoauthlibto 20200912 or later.