Summary
Workarounds
Reject RSA PKCS1-v1_5 or RSA-OAEP encrypted message with unnecessary prepending zeros.
References
https://nvd.nist.gov/vuln/detail/CVE-2020-14967
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14967
https://vuldb.com/?id.157124
https://kjur.github.io/jsrsasign/api/symbols/KJUR.crypto.Cipher.html#.decrypt
https://github.com/kjur/jsrsasign/issues/439
Impact
Jsrsasign supports RSA PKCS#1 v1.5 (i.e. RSAES-PKCS1-v1_5) and RSA-OAEP encryption and decryption. Its encrypted message is represented as BigInteger. When there is a valid encrypted message, a crafted message with prepending zeros can be decrypted by this vulnerability.
- If you don't use RSA PKCS1-v1_5 or RSA-OAEP decryption, this vulnerability is not affected.
- Risk to forge contents of encrypted message is very low.
- Risk to raise memory corruption is low since jsrsasign uses BigInteger class.
CVE-2020-14967 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (8.0.18); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Users using RSA PKCS1-v1_5 or RSA-OAEP decryption should upgrade to 8.0.18.
Frequently Asked Questions
- What is CVE-2020-14967? CVE-2020-14967 is a critical-severity security vulnerability in jsrsasign (npm), affecting versions < 8.0.18. It is fixed in 8.0.18.
- How severe is CVE-2020-14967? CVE-2020-14967 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of jsrsasign are affected by CVE-2020-14967? jsrsasign (npm) versions < 8.0.18 is affected.
- Is there a fix for CVE-2020-14967? Yes. CVE-2020-14967 is fixed in 8.0.18. Upgrade to this version or later.
- Is CVE-2020-14967 exploitable, and should I be worried? Whether CVE-2020-14967 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-14967 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-14967? Upgrade
jsrsasignto 8.0.18 or later.