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MEDIUM severity

CVE-2021-29446 — jose-node-cjs-runtime

MEDIUM

CVE-2021-29446 is a medium-severity (CVSS 5.9) CWE-203 vulnerability in jose-node-cjs-runtime. A fix is available for jose-node-cjs-runtime — see the affected versions and patch details below.

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

Also known asGHSA-rvcw-f68w-8h8h
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs65th percentile — riskier than 65% of all scored CVEsHighest risk
0.00%0.58%1.16%1.74%0.4%1.1%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

3other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
jose-node-cjs-runtimenpm
10Kdownloads / week

Description

Impact

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).

Patches

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.

Credits

Thanks to Morgan Brown of Microsoft for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmjose-node-cjs-runtimeall versions3.11.4npm install jose-node-cjs-runtime@3.11.4

Affected Products

1 product · 1 configurations
Application
jose-node-cjs-runtimejose-node-cjs-runtime_project
< 3.11.4
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jose-node-cjs-runtime, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update jose-node-cjs-runtime to 3.11.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29446 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact [AES_CBC_HMAC_SHA2 Algorithm](https://tools.ietf.org/html/rfc7518#section-5.2) (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 byte
O3 Security · Impact-Aware SCA

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CVE-2021-29446: jose-node-cjs-runtime — Fixed in 3.11.4