CVE-2026-4258

Name: CVE-2026-4258
Creator: NVD / NIST
Published: 2026-03-17T06:16:18.59+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.7/10EPSS 0.25%

Last modified Jun 17, 2026

CVE-2026-4258 is a high-severity vulnerability rated 7.7/10 on the CVSS scale. 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. EPSS estimates a 0.25% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

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

CVSS 4.0

7.7/10

CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.25%

15.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Bitwiseshiftleft	Stanford Javascript Crypto Library	<= 1.0.8

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-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

Timeline

Published: Mar 17, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-4258?

How severe is CVE-2026-4258?

CVE-2026-4258 has a CVSS score of 7.7/10 (HIGH severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.

How do I fix CVE-2026-4258?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-4258?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST