CVE-2021-29444 Padding Oracle Attack due to Observable Timing Discrepancy in jose-browser-runtime

2021-04-1621:45:16

CWE-203

GitHub_M

www.cve.org

5.9 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

6.4 Medium

AI Score

Confidence

High

0.001 Low

EPSS

Percentile

51.2%

JSON

jose-browser-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.

CNA Affected

[
  {
    "product": "jose",
    "vendor": "panva",
    "versions": [
      {
        "status": "affected",
        "version": "< 3.11.4"
      }
    ]
  }
]