CVE-2021-29446CWE-203

Padding Oracle Attack due to Observable Timing Discrepancy in jose-node-cjs-runtime

Medium · published April 16, 2021

CVSS v3.1
5.9
EPSS
1%
Percentile
64.5
In the wild
Unconfirmed
What it is

jose-node-cjs-runtime is an npm package which provides a number of cryptographic functions. In versions prior to 3.11.4 the 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. 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). A patch was released which ensures the HMAC tag is verified before performing CBC decryption. The fixed versions are `>=3.11.4`. Users should upgrade to `^3.11.4`.

The record
Technical detail
CVSS v3.1
5.9 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.01067 · 64.5th percentile
Weakness
CWE-203 · Observable Discrepancy
Published
2021-04-16T22:00Z
EPSS history
Timeline
  • 16 APR 22:00Z
    Padding Oracle Attack due to Observable Timing Discrepancy in jose-node-cjs-runtime
    cvelistv5