CVE-2020-14966 ECDSA signature validation vulnerability by accepting wrong ASN.1 encoding in jsrsasign

What is CVE-2020-14966?

CVE-2020-14966 is a high-severity vulnerability in n/a, published on 22 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An issue was discovered in the jsrsasign package through 8.0.18 for Node.js. It allows a malleability in ECDSA signatures by not checking overflows in the length of a sequence and '0' characters appended or prepended to an integer. The modified signatures are verified as valid. This could have a security-relevant impact if an application relied on a single canonical signature.

Weakness: CWE-347

Which versions are affected by CVE-2020-14966?

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

Products include Kjur Jsrsasign, Netapp Max Data.

How do I fix CVE-2020-14966?

Upgrade jsrsasign to 8.0.19 or later.

Is CVE-2020-14966 being exploited?

There is no known exploitation of CVE-2020-14966 in the wild and no public exploit code.

Other vulnerabilities in n/a

• CVE-2020-14967 RSA PKCS#1 decryption vulnerability with prepending zeros in jsrsasign Critical 9.8
• CVE-2020-14968 RSA-PSS signature validation vulnerability by prepending zeros in jsrsasign Critical 9.8
• CVE-2026-4601 jsrsasign: Missing cryptographic validation during DSA signing enables private key extraction Critical 9.4
• CVE-2026-4599 jsrsasign: Incomplete Comparison Allows DSA Private Key Recovery via Biased Nonce Generation Critical 9.3
• 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

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-p8c3-7rj8-q963.