Vulnerability Description
All versions of the package sjcl are vulnerable to Improper Verification of Cryptographic Signature due to missing point-on-curve validation in sjcl.ecc.basicKey.publicKey(). An attacker can recover a victim's ECDH private key by sending crafted off-curve public keys and observing ECDH outputs. The dhJavaEc() function directly returns the raw x-coordinate of the scalar multiplication result (no hashing), providing a plaintext oracle without requiring any decryption feedback.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47
- https://github.com/bitwiseshiftleft/sjcl/blob/master/core/ecc.js%23L454-L461
- https://github.com/bitwiseshiftleft/sjcl/commit/ee307459972442a17beebc29dc331fff
- https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617
- https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47
- https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617
FAQ
What is CVE-2026-4258?
CVE-2026-4258 is a vulnerability with a CVSS score of 7.5 (HIGH). All versions of the package sjcl are vulnerable to Improper Verification of Cryptographic Signature due to missing point-on-curve validation in sjcl.ecc.basicKey.publicKey(). An attacker can recover a...
How severe is CVE-2026-4258?
CVE-2026-4258 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-4258?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.