jwcrypto token substitution can lead to authentication bypass
The JWT code can auto-detect the type of token being provided, and this can lead the application to incorrect conclusions about the trustworthiness of the token.
Quoting the private disclosure we received : "Under certain circumstances, it is possible to substitute a [..] signed JWS with a JWE that is encrypted with the public key that is normally used for signature validation."
This substitution attack can occur only if the validating application also have access to the private key, normally used to sign the tokens, available during validation of the received JWT.
The significance of this attacks depends on the use of the token, it may lead
JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to 1.5.7, an unauthenticated attacker can exhaust server memory by sending crafted JWE tokens with ZIP compression. The existing patch for CVE-2024-28102 limits input token size to 250KB but does not validate the decompressed output size. An unauthenticated attacker can cause memory exhaustion on memory-constrained systems. A token under the 250KB input limit can decompress to approximately 100MB. This vulnerability is fixed in 1.5.7.
JWCrypto vulnerable to JWT bomb Attack in `deserialize` function
JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to version 1.5.6, an attacker can cause a denial of service attack by passing in a malicious JWE Token with a high compression ratio. When the server processes this token, it will consume a lot of memory and processing time. Version 1.5.6 fixes this vulnerability by limiting the maximum token length.
Jwcrypto: denail of service via specifically crafted jwe
A vulnerability was found in JWCrypto. This flaw allows an attacker to cause a denial of service (DoS) attack and possible password brute-force and dictionary attacks to be more resource-intensive. This issue can result in a large amount of computational consumption, causing a denial of service attack.
The _Rsa15 class in the RSA 1.5 algorithm implementation in jwa.py in jwcrypto before 0.3.2 lacks the Random Filling protection mechanism, which makes it easier for remote attackers to obtain cleartext data via a Million Message Attack (MMA).