CVE-2026-4258: Versions of the package sjcl before 1.0.9 are vulnerable to Improper Verification of Cryptographic Signature d

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HIGH 7.5REMOTEUPGRADE

CVE-2026-4258 is a high-severity flaw (CVSS 7.5) affecting stanford javascript crypto library. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 with

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 83%)
CISA exploited list	No
Weakness	CWE-347, CWE-325
Published	2026-03-17
Last modified	2026-07-28

Publisher (CNA): Snyk · Vendor: bitwiseshiftleft

Last updated 2026-07-28 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-17 06:16 UTCPublished CVE record published
2026-07-28 16:18 UTCUpdated Record last modified

bitwiseshiftleft stanford javascript crypto library UPGRADE

Affected: <= 1.0.8

Fixed in: newer than 1.0.8

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls stanford-javascript-crypto-library

2. UPGRADE to newer than 1.0.8

npm install stanford-javascript-crypto-library@">1.0.8"

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-4258?

stanford javascript crypto library: upgrade to newer than 1.0.8. Exact commands for each OS are on this page.

Is CVE-2026-4258 being exploited?

CVE-2026-4258 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-4258 affect?

CVE-2026-4258 affects stanford javascript crypto library. Severity is high (CVSS 7.5). 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 s

How urgent is CVE-2026-4258?

Priority 41/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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