CVE-2026-23965
Published: 22 January 2026
Summary
CVE-2026-23965 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, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); 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 SC-13 (Cryptographic Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-23965 is a signature forgery vulnerability in the SM2 signature verification logic of the sm-crypto JavaScript library, which provides implementations of the Chinese cryptographic algorithms SM2, SM3, and SM4. The flaw affects versions of sm-crypto prior to 0.4.0 and is classified under CWE-347. It was published on 2026-01-22 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), highlighting high integrity impact.
Remote attackers require no privileges or user interaction to exploit the vulnerability under default configurations. They can forge valid SM2 signatures for arbitrary public keys, potentially bypassing authentication or integrity checks in applications relying on the library. If the message space contains sufficient redundancy, attackers can fix the prefix of the associated message to satisfy specific formatting requirements, enabling targeted forgery.
The issue is patched in sm-crypto version 0.4.0. Security practitioners should upgrade to this version immediately. Further details, including the patch commit, are available at https://github.com/JuneAndGreen/sm-crypto/commit/85295a859d0766222d12ce2be3e6fce7b438b510, and the GitHub security advisory at https://github.com/JuneAndGreen/sm-crypto/security/advisories/GHSA-hpwg-xg7m-3p6m.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3674
Vulnerability details
sm-crypto provides JavaScript implementations of the Chinese cryptographic algorithms SM2, SM3, and SM4. A signature forgery vulnerability exists in the SM2 signature verification logic of sm-crypto prior to version 0.4.0. Under default configurations, an attacker can forge valid signatures for…
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arbitrary public keys. If the message space contains sufficient redundancy, the attacker can fix the prefix of the message associated with the forged signature to satisfy specific formatting requirements. Version 0.4.0 patches the issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated signature forgery in a cryptographic library directly enables exploitation of public-facing applications relying on SM2 signature verification for auth/integrity.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires cryptographic or equivalent mechanisms to verify the integrity of software, firmware, and information, which the flawed SM2 signature verification in sm-crypto fails to provide.
Mandates the use of approved cryptographic mechanisms for protection, directly addressing the broken SM2 signature verification that allows forgery under default configurations.
Requires timely installation of patches to correct identified flaws, which resolves this signature forgery vulnerability via the upgrade to sm-crypto 0.4.0.