What is CVE-2021-29443?

CVE-2021-29443 is a medium-severity vulnerability in Jose Project, classified under Observable Discrepancy. CVSS score: 5.9/10. Published 2021-04-16.

How severe is CVE-2021-29443?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Jose Project

CVE-2021-29443

jose is an npm library providing a number of cryptographic operations. In vulnerable versions 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. 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). 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, their v2.x dependency to ^2.0.5, and their v3.x dependency to ^3.11.4. Thanks to Jason from Microsoft Vulnerability Research (MSVR) for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.

Published 2021-04-16 · last modified 2026-06-22.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.012 (66.1th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 66.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Jose Project
Panva Jose — versions < 1.28.1, >= 2.0.0, < 2.0.5, >= 3.0.0, < 3.11.4

Weakness classification (CWE)

CWE-203 — Observable Discrepancy

References

github.com/panva/jose/security/advisories/GHSA-58f5-hfqc-jgch (Patch, Third Party Advisory)
www.npmjs.com/package/jose (Third Party Advisory)

Frequently asked questions

What is CVE-2021-29443?: CVE-2021-29443 is a medium-severity vulnerability in Jose Project, classified under Observable Discrepancy. CVSS score: 5.9/10. Published 2021-04-16.
How severe is CVE-2021-29443?: Medium severity. CVSS v3 base score is 5.9 out of 10.