CVE-2026-4258: sjcl is missing point-on-curve validation in sjcl.ecc.basicKey.publicKey
(updated )
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.
References
- gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47
- github.com/advisories/GHSA-2w8x-224x-785m
- github.com/bitwiseshiftleft/sjcl
- github.com/bitwiseshiftleft/sjcl/blob/master/core/ecc.js
- github.com/bitwiseshiftleft/sjcl/commit/ee307459972442a17beebc29dc331fffd8aff796
- nvd.nist.gov/vuln/detail/CVE-2026-4258
- security.snyk.io/vuln/SNYK-JS-SJCL-15369617
Code Behaviors & Features
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