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.
CVE-2026-4258
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.0%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EPSS
- 15.9%
- KEV
- Not listed
Published
March 17, 2026
Last Modified
June 3, 2026
Advisory Details (3)
Auto-updated Jun 12, 2026Improper Verification of Cryptographic Signature in sjcl | CVE-2026-4258 | Snyk
https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617SJCL Invalid Curve Attack.md · GitHub
https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47commit ee3074599724 (bitwiseshiftleft/sjcl)
Fix landed in bitwiseshiftleft/sjcl commit ee3074599724 — awaiting tagged release
https://github.com/bitwiseshiftleft/sjcl/commit/ee307459972442a17beebc29dc331fffd8aff796Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| sjcl | — | 1.0.9 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 37× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:08 UTCEPSS rescore
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- 2026-06-30 23:22 UTCEPSS rescore
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- 2026-06-29 06:02 UTCOSV refresh
- 2026-06-28 14:07 UTCEPSS rescore
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- 2026-06-05 06:10 UTCEPSS rescore
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- 2026-06-04 13:12 UTCEPSS rescore
- 2026-06-04 13:12 UTCEPSS rescore
- 2026-06-03 15:12 UTCEG score recompute
Related CVEs(same CWE)
Same CWE
10 shownCWE-347
Frequently asked(5)
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