CVE-2020-14967
RSA PKCS#1 decryption vulnerability with prepending zeros in jsrsasign
An issue was discovered in the jsrsasign package before 8.0.18 for Node.js. Its RSA PKCS1 v1.5 decryption implementation does not detect ciphertext modification by prepending '\0' bytes to ciphertexts (it decrypts modified ciphertexts without error). An attacker might prepend these bytes with the goal of triggering memory corruption issues.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
An issue was discovered in the jsrsasign package before 8.0.18 for Node.js. Its RSA PKCS1 v1.5 decryption implementation does not detect ciphertext modification by prepending '\0' bytes to ciphertexts (it decrypts modified ciphertexts without error). An attacker might prepend these bytes with the goal of triggering memory corruption issues.
- Record
CVE-2020-14967- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-119
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in the jsrsasign package before 8.0.18 for Node.js. Its RSA PKCS1 v1.5 decryption implementation does not detect ciphertext modification by prepending '\0' bytes to ciphertexts (it decrypts modified ciphertexts without error). An attacker might prepend these bytes with the goal of triggering memory corruption issues.
- Record
CVE-2020-14967- Updated
- 2026-11-02
EUVDEUVD-2020-0526 No score
An issue was discovered in the jsrsasign package before 8.0.18 for Node.js. Its RSA PKCS1 v1.5 decryption implementation does not detect ciphertext modification by prepending '\0' bytes to ciphertexts (it decrypts modified ciphertexts without error). An attacker might prepend these bytes with the goal of triggering memory corruption issues.
- Record
EUVD-2020-0526- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-xxxq-chmp-67g4
RSA PKCS#1 decryption vulnerability with prepending zeros in jsrsasign
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.
Patches
Users using RSA PKCS1-v1_5 or RSA-OAEP decryption should upgrade to 8.0.18.
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
- Record
GHSA-xxxq-chmp-67g4- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-119
- Updated
- 2026-11-02
OSV
An issue was discovered in the jsrsasign package before 8.0.18 for Node.js. Its RSA PKCS1 v1.5 decryption implementation does not detect ciphertext modification by prepending '\0' bytes to ciphertexts (it decrypts modified ciphertexts without error). An attacker might prepend these bytes with the goal of triggering memory corruption issues.
- Record
CVE-2020-14967- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVGHSA-xxxq-chmp-67g4
RSA PKCS#1 decryption vulnerability with prepending zeros in jsrsasign
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.
Patches
Users using RSA PKCS1-v1_5 or RSA-OAEP decryption should upgrade to 8.0.18.
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
- Record
GHSA-xxxq-chmp-67g4- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-119
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
jsrsasignnpm |
before 8.0.18 | 8.0.18 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-14967 is a critical vulnerability (CVSS 9.8) in Kjur Jsrsasign, published June 22, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.27%, the 83rd percentile. Fixed in jsrsasign 8.0.18.
References
kjur.github.io/jsrsasign
npmjs.com/package/jsrsasign
github.com/kjur/jsrsasign/releases/tag/8.0.18
security.netapp.com/advisory/ntap-20200724-0001
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nvd.nist.gov/vuln/detail/CVE-2020-14967
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14967
vuldb.com?id.157124