CVE-2026-34610 (GCVE-0-2026-34610)

Vulnerability from cvelistv5 – Published: 2026-04-02 17:54 – Updated: 2026-04-03 17:25
VLAI
Title
leancrypto: Integer truncation in X.509 name parser enables certificate identity impersonation
Summary
The leancrypto library is a cryptographic library that exclusively contains only PQC-resistant cryptographic algorithms. Prior to version 1.7.1, lc_x509_extract_name_segment() casts size_t vlen to uint8_t when storing the Common Name (CN) length. An attacker who crafts a certificate with CN = victim's CN + 256 bytes padding gets cn_size = (uint8_t)(256 + N) = N, where N is the victim's CN length. The first N bytes of the attacker's CN are the victim's identity. After parsing, the attacker's certificate has an identical CN to the victim's — enabling identity impersonation in PKCS#7 verification, certificate chain matching, and code signing. This issue has been patched in version 1.7.1.
Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-04-03 17:03 UTC
CWE
  • CWE-681 - Incorrect Conversion between Numeric Types
Assigner
GitHub_M CNA
References
Impacted products
Vendor Product Version
smuellerDD leancrypto Affected: < 1.7.1
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