CVE-2021-29446

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

MEDIUM
5.9
CVSS Score
Published: April 16, 2021 at 10:00 PM UTC
Updated: June 17, 2026 at 03:47 AM UTC
2 products affected across 2 vendorsJose Node Cjs RuntimeNode Cjs Runtime Project Jose Node Cjs Runtime

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Severity
MEDIUM5.9
Exploit prediction
EPSS 1%

Description

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`.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.11.4
Affected range stops below 3.11.4, so it looks safe — our inference, not a vendor statement
v < 3.11.4
Affected range stops below 3.11.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (2)

CVSS

5.9MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-203

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