CVE-2021-29445 Padding Oracle Attack due to Observable Timing Discrepancy in jose-node-esm-runtime

2021-04-1621:50:13

CWE-203

GitHub_M

www.cve.org

cve-2021-29445

padding oracle attack

jose-node-esm-runtime

observable timing discrepancy

aes cbc hmac

jwedecryptionfailed

cbc decryption

hmac tag verification

patch

upgrade

CVSS3

5.9

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

AI Score

6.4

Confidence

High

EPSS

0.001

Percentile

51.2%

JSON

jose-node-esm-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-node-esm-runtime",
    "vendor": "panva",
    "versions": [
      {
        "status": "affected",
        "version": "< 3.11.4"
      }
    ]
  }
]