# CVE-2021-30246: RSA signature validation vulnerability on maleable encoded message in jsrsasign

> The jsrsasign library incorrectly validates certain invalid RSA signatures, potentially allowing attackers to bypass cryptographic verification mechanisms.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-27fj-mc8w-j9wg

## What is CVE-2021-30246?

CVE-2021-30246 is a critical vulnerability in n/a, published on 7 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the jsrsasign package through 10.1.13 for Node.js, some invalid RSA PKCS#1 v1.5 signatures are mistakenly recognized to be valid. NOTE: there is no known practical attack.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2021-30246?

2 open source packages ship an affected version, including jsrsasign. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `jsrsasign` | npm | All versions | 10.2.0 |
| `jsrsasign` | npm | All versions | 10.2.0 |

Products: Kjur Jsrsasign.

## How do I fix CVE-2021-30246?

Upgrade jsrsasign to 10.2.0 or later.

## Is CVE-2021-30246 being exploited?

There is no known exploitation of CVE-2021-30246 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-14967](https://insights.sbomify.com/CVE-2020-14967/): RSA PKCS#1 decryption vulnerability with prepending zeros in jsrsasign (critical 9.8)
- [CVE-2020-14968](https://insights.sbomify.com/CVE-2020-14968/): RSA-PSS signature validation vulnerability by prepending zeros in jsrsasign (critical 9.8)
- [CVE-2026-4601](https://insights.sbomify.com/CVE-2026-4601/): jsrsasign: Missing cryptographic validation during DSA signing enables private key extraction (critical 9.4)
- [CVE-2026-4599](https://insights.sbomify.com/CVE-2026-4599/): jsrsasign: Incomplete Comparison Allows DSA Private Key Recovery via Biased Nonce Generation (critical 9.3)
- [CVE-2026-4600](https://insights.sbomify.com/CVE-2026-4600/): jsrsasign: DSA signatures or X.509 certificates can be forged via DSA domain-parameter validation in KJUR.crypto.DSA.setPublic (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-30246 and fix it if it is affected.

What it is: CVE-2021-30246 is a critical vulnerability in n/a, published on 7 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-30246 in the wild and no public exploit code.

Affected packages and fixed versions:
- jsrsasign (npm): affected all versions; fixed in 10.2.0
- jsrsasign (npm): affected all versions; fixed in 10.2.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-30246/ (Markdown: https://insights.sbomify.com/CVE-2021-30246/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-30246
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-30246
- OSV: https://osv.dev/vulnerability/CVE-2021-30246

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-30246/
Summaries are generated and may contain mistakes; the official description above is the record.