Vulnerability in Bitwiseshiftleft Stanford JavaScript Crypto Library
CVE-2026-4258
Versions of the package sjcl before 1.0.9 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.
EPSS: 0.002 (15.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
Affected products
- Bitwiseshiftleft Stanford_javascript_crypto_library
- N/a Org.webjars.npm:sjcl — versions 0
- N/a Sjcl — versions 0
Weakness classification (CWE)
References
- report@snyk.io (Exploit, Third Party Advisory)
- report@snyk.io (Exploit, Third Party Advisory, Mitigation)
- report@snyk.io (Broken Link)
- report@snyk.io (Patch)
- report@snyk.io
Frequently asked questions
- What is CVE-2026-4258?
- CVE-2026-4258 is a high-severity vulnerability in Bitwiseshiftleft Stanford JavaScript Crypto Library, classified under Improper Verification of Cryptographic Signature. CVSS score: 7.5/10. Published 2026-03-17.
- How severe is CVE-2026-4258?
- High severity. CVSS v3 base score is 7.5 out of 10.