CVE-2026-4258: Bitwiseshiftleft Stanford JavaScript Crypto Library vulnerability (CVSS 7.5)

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 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Affected products

Bitwiseshiftleft Stanford JavaScript Crypto Library≤ 1.0.8

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

Patch & vendor advisories

https://github.com/bitwiseshiftleft/sjcl/commit/ee307459972442a17beebc29dc331fffd8aff796

References

https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47ExploitMitigationThird 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-15369617ExploitThird Party Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-4258 being actively exploited?

CVE-2026-4258 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.34%.

How severe is CVE-2026-4258?

CVE-2026-4258 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.34% probability of exploitation.

Which products are affected by CVE-2026-4258?

Affected products include Bitwiseshiftleft Stanford JavaScript Crypto Library.

How do I fix CVE-2026-4258?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-4258 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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