How severe is CVE-2026-4258?

CVE-2026-4258 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-4258 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4258?

CVE-2026-4258 affects Bitwiseshiftleft Stanford Javascript Crypto Library. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4258?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-4258 have an EU (EUVD) identifier?

Yes. CVE-2026-4258 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12542.

When was CVE-2026-4258 published?

CVE-2026-4258 was published on 2026-03-17 and last updated on 2026-06-17.

CVE-2026-4258

CVE-2026-4258 is a high-severity vulnerability in Bitwiseshiftleft Stanford Javascript Crypto Library with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 7.7
EPSS exploit prediction: 0% (16th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12542
Weakness: CWE-347
Affected product: Bitwiseshiftleft Stanford Javascript Crypto Library
Published: 2026-03-17
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-4258?: 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.
How severe is CVE-2026-4258?: CVE-2026-4258 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-4258 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4258?: CVE-2026-4258 affects Bitwiseshiftleft Stanford Javascript Crypto Library. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4258?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-4258 have an EU (EUVD) identifier?: Yes. CVE-2026-4258 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12542.
When was CVE-2026-4258 published?: CVE-2026-4258 was published on 2026-03-17 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:bitwiseshiftleft:stanford_javascript_crypto_library:*:*:*:*:*:node.js:*:*

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