CVE-2021-29443
MediumCVSS 5.9Exploitation Probability (EPSS)
Elevated risk63th percentile - higher than 63% of all known CVEs
Summary
The jose library, used for cryptographic operations, has a vulnerability in the AES_CBC_HMAC_SHA2 algorithm that allows the use of a padding oracle to decrypt data without knowing the key. Observable timing differences during padding errors can enable an attacker to exploit this vulnerability.
Risk Assessment
Organizations may be exposed to unauthorized access to sensitive data, potentially leading to serious security breaches and loss of customer trust.
Recommendation
It is recommended to upgrade the jose library to version ^1.28.1 for v1.x, ^2.0.5 for v2.x, and >=3.11.4 for v3.x to mitigate this vulnerability.
Original NVD description (English source)
jose is an npm library providing a number of cryptographic operations. In vulnerable versions AES_CBC_HMAC_SHA2 Algorithm (A128CBC-HS256, A192CBC-HS384, A256CBC-HS512) decryption would always execute both HMAC tag verification and CBC decryption, if either failed `JWEDecryptionFailed` would be thrown. A possibly observable difference in timing when padding error would occur while decrypting the ciphertext makes a padding oracle and an adversary might be able to make use of that oracle to decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block). All major release versions have had a patch released which ensures the HMAC tag is verified before performing CBC decryption. The fixed versions are `^1.28.1 || ^2.0.5 || >=3.11.4`. Users should upgrade their v1.x dependency to ^1.28.1, their v2.x dependency to ^2.0.5, and their v3.x dependency to ^3.11.4. Thanks to Jason from Microsoft Vulnerability Research (MSVR) for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.