CVE-2021-29443
Padding Oracle Attack due to Observable Timing Discrepancy in jose
Description
jose is an npm library providing a number of cryptographic operations. ### Impact [AES_CBC_HMAC_SHA2 Algorithm](https://tools.ietf.org/html/rfc7518#section-5.2) (A128CBC-HS256, A192CBC-HS384, A256CBC-HS512) decryption would always execute both HMAC tag verification and CBC decryption, if either failed `JWEDecryptionFailed` would be thrown. But 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). ### Patches 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`](https://github.com/panva/jose/releases/tag/v1.28.1), their v2.x dependency to [`^2.0.5`](https://github.com/panva/jose/releases/tag/v2.0.5), and their v3.x dependency to [`^3.11.4`](https://github.com/panva/jose/releases/tag/v3.11.4) ### Credits Thanks to Morgan Brown of Microsoft for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.
How to fix CVE-2021-29443
To remediate CVE-2021-29443, upgrade the affected package to a fixed version below.
- —upgrade to 1.28.1 or later
Is CVE-2021-29443 being exploited?
Low — EPSS is 1.2%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 1.0.0, < 1.28.1