The Flask-Caching extension through 1.10.1 for Flask relies on Pickle for serialization, which may lead to remote code execution or local privilege escalation. If an attacker gains access to cache storage (e.g., filesystem, Memcached, Redis, etc.), they can construct a crafted payload, poison the cache, and execute Python code. NOTE: a third party indicates that exploitation is extremely unlikely unless the machine is already compromised; in other cases, the attacker would be unable to write their payload to the cache and generate the required collision
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Flask-caching | Flask-caching_project | * | 1.10.1 (including) |
| Flask-caching | Ubuntu | groovy | * |
| Flask-caching | Ubuntu | hirsute | * |
| Flask-caching | Ubuntu | impish | * |
| Flask-caching | Ubuntu | kinetic | * |
| Flask-caching | Ubuntu | lunar | * |
| Flask-caching | Ubuntu | mantic | * |
| Flask-caching | Ubuntu | trusty | * |
| Flask-caching | Ubuntu | upstream | * |
| Flask-caching | Ubuntu | xenial | * |
It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.