PyJWT is a Python implementation of RFC 7519. PyJWT supports multiple different JWT signing algorithms. With JWT, an attacker submitting the JWT token can choose the used signing algorithm. The PyJWT library requires that the application chooses what algorithms are supported. The application can specify jwt.algorithms.get_default_algorithms() to get support for all algorithms, or specify a single algorithm. The issue is not that big as algorithms=jwt.algorithms.get_default_algorithms() has to be used. Users should upgrade to v2.4.0 to receive a patch for this issue. As a workaround, always be explicit with the algorithms that are accepted and expected when decoding.
The product uses a broken or risky cryptographic algorithm or protocol.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Pyjwt | Pyjwt_project | 1.5.0 (including) | 2.4.0 (excluding) |
| Pyjwt | Ubuntu | bionic | * |
| Pyjwt | Ubuntu | focal | * |
| Pyjwt | Ubuntu | impish | * |
| Pyjwt | Ubuntu | jammy | * |
| Pyjwt | Ubuntu | upstream | * |
Cryptographic algorithms are the methods by which data is scrambled to prevent observation or influence by unauthorized actors. Insecure cryptography can be exploited to expose sensitive information, modify data in unexpected ways, spoof identities of other users or devices, or other impacts. It is very difficult to produce a secure algorithm, and even high-profile algorithms by accomplished cryptographic experts have been broken. Well-known techniques exist to break or weaken various kinds of cryptography. Accordingly, there are a small number of well-understood and heavily studied algorithms that should be used by most products. Using a non-standard or known-insecure algorithm is dangerous because a determined adversary may be able to break the algorithm and compromise whatever data has been protected. Since the state of cryptography advances so rapidly, it is common for an algorithm to be considered “unsafe” even if it was once thought to be strong. This can happen when new attacks are discovered, or if computing power increases so much that the cryptographic algorithm no longer provides the amount of protection that was originally thought. For a number of reasons, this weakness is even more challenging to manage with hardware deployment of cryptographic algorithms as opposed to software implementation. First, if a flaw is discovered with hardware-implemented cryptography, the flaw cannot be fixed in most cases without a recall of the product, because hardware is not easily replaceable like software. Second, because the hardware product is expected to work for years, the adversary’s computing power will only increase over time.