CVE-2026-4258
High
Description
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductSjcl
PublishedMar 17, 2026
First seenMar 17, 2026
Weakness typeCWE-347CWE-347
How to fix
Update
- sjcl1.0.9 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| sjclnpm | v < 1.0.9 | 1.0.9 |
| bitwiseshiftleft stanford_javascript_crypto_library | v ≤ 1.0.8 | — |
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