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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2021-29445: 1.07% estimated exploitation activity in the next 30 days; percentile 64.83 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact AESCBCHMACSHA2 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 128b 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.

Published by the source

19 Apr 2021, 14:59 UTC

Last modified by the source

8 Jul 2026, 06:29 UTC

Source last checked

26 Oct 2026, 12:21 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4v4g-726h-xvfv

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4v4g-726h-xvfv

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# Patch Next advisory brief: CVE-2021-29445

Advisory: Padding Oracle Attack due to Observable Timing Discrepancy in jose-node-esm-runtime
IDs: CVE-2021-29445, GHSA-4v4g-726h-xvfv
Record: https://patchnext.com/advisories/cve-2021-29445 (revision 2, source checked 26 Oct 2026, 12:21 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: jose-node-esm-runtime 3.11.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm jose-node-esm-runtime: affected < 3.11.4; fixed in 3.11.4

## Suggested inspection (read-only)
- `npm ls jose-node-esm-runtime --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on jose-node-esm-runtime.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-4v4g-726h-xvfv (OSV record GHSA-4v4g-726h-xvfv lists affected ranges: npm jose-node-esm-runtime >=0 <3.11.4 (fixed))
- Verified: https://github.com/advisories/GHSA-4v4g-726h-xvfv (GitHub-reviewed advisory GHSA-4v4g-726h-xvfv lists affected ranges: npm jose-node-esm-runtime >=0 <3.11.4)

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