Vulnerability Details CVE-2026-4258
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 15.5%
CVSS Severity
CVSS v3 Score 7.5
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/ee307459972442a17beebc29dc331fffd8aff796
- https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617
- https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47
- https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617
Products affected by CVE-2026-4258
-
cpe:2.3:a:bitwiseshiftleft:stanford_javascript_crypto_library:*