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Vulnerability record · CVE-2026-4258 · published 17 March 2026

CVE-2026-4258: Bitwiseshiftleft stanford javascript crypto library improper verification of cryptographic signature vulnerability

BBitwiseshiftleft · Stanford Javascript Crypto Library

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.

7.7 CVSS 4.0 High EPSS 0.34% · top 74.7% CWE-347 · Improper verification of cryptographic signatureCWE-325 · CWE-325
7.7CVSS 4.0 base score
0.34%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
7References, 4 tagged exploit
28 Jul 2026Last modified by NVD

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: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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47 ExploitMitigationThird Party Advisory
https://github.com/bitwiseshiftleft/sjcl/blob/master/core/ecc.js%23L454-L461 Broken Link
https://github.com/bitwiseshiftleft/sjcl/commit/ee307459972442a17beebc29dc331fffd8aff796 Patch
https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-15751243
https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617 ExploitThird Party Advisory
https://gist.github.com/Kr0emer/2560f98edb10b0b34f2438cd63913c47 ExploitMitigationThird Party Advisory
https://security.snyk.io/vuln/SNYK-JS-SJCL-15369617 ExploitThird Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-4258), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.