CVE-2026-4258 | THREATINT

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.

PUBLISHED Reserved 2026-03-16 | Published 2026-03-17 | Updated 2026-03-17 | Assigner snyk

HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:P

Problem types

Improper Verification of Cryptographic Signature

Credits

Kr0emer

References

gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47 exploit

security.snyk.io/vuln/SNYK-JS-SJCL-15369617 exploit

security.snyk.io/vuln/SNYK-JS-SJCL-15369617

gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47

github.com/...iftleft/sjcl/blob/master/core/ecc.js#L454-L461

github.com/...ommit/ee307459972442a17beebc29dc331fffd8aff796

cve.org (CVE-2026-4258)

nvd.nist.gov (CVE-2026-4258)

Download JSON