CVE-2026-23967
Published: 22 January 2026
Summary
CVE-2026-23967 is a high-severity Improper Verification of Cryptographic Signature (CWE-347) vulnerability in Juneandgreen Sm-Crypto. Its CVSS base score is 7.5 (High).
Operationally, ranked at the 1.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and AU-10 (Non-repudiation).
Deeper analysis
CVE-2026-23967 is a signature malleability vulnerability in the SM2 signature verification logic of the sm-crypto JavaScript library, which implements the Chinese cryptographic algorithms SM2, SM3, and SM4. The issue affects versions of sm-crypto prior to 0.3.14, allowing an attacker to derive a new valid signature for a previously signed message from an existing one. It is rated with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N) and maps to CWE-347 (Improper Verification of Cryptographic Signature).
Any remote attacker can exploit this vulnerability without privileges or user interaction over the network with low complexity. By obtaining a valid SM2 signature for a message, the attacker can malleate it to produce another valid signature for the same message, potentially enabling signature forgery in applications relying on sm-crypto for SM2 verification. This leads to high integrity impact, undermining the non-repudiation properties of signatures.
The GitHub security advisory at https://github.com/JuneAndGreen/sm-crypto/security/advisories/GHSA-qv7w-v773-3xqm details the vulnerability, confirming that upgrading to version 0.3.14 of sm-crypto patches the issue by addressing the malleability flaw in the SM2 verification logic. Security practitioners should audit dependencies for vulnerable sm-crypto versions and apply the update promptly.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3675
Vulnerability details
sm-crypto provides JavaScript implementations of the Chinese cryptographic algorithms SM2, SM3, and SM4. A signature malleability vulnerability exists in the SM2 signature verification logic of the sm-crypto library prior to version 0.3.14. An attacker can derive a new valid signature…
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for a previously signed message from an existing signature. Version 0.3.14 patches the issue.
- CWE(s)
Related Threats
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely remediation of known flaws in software components such as the vulnerable sm-crypto library prior to version 0.3.14.
Protects against false denial of origin or receipt by ensuring cryptographic signatures cannot be malleated to produce additional valid signatures for the same message.
Mandates correct implementation and use of cryptographic mechanisms so that SM2 signature verification enforces intended integrity and non-repudiation properties.