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().
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.25%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 4.0
- 7.7 HIGHCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.25% probability · 16th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-347, CWE-325
- Affected
- bitwiseshiftleft/stanford javascript crypto library
- Source
- report@snyk.io
References
- https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47Exploit, Mitigation, Third Party Advisory
- https://github.com/bitwiseshiftleft/sjcl/blob/master/core/ecc.js%23L454-L461Broken Link
- https://github.com/bitwiseshiftleft/sjcl/commit/ee307459972442a17beebc29dc331fffd8aff796Patch
- https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-15751243
- https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617Exploit, Third Party Advisory
- https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47Exploit, Mitigation, Third Party Advisory
- https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617Exploit, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.