CVE-2026-34610
MediumCVSS 5.9Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
Vulnerability in the leancrypto cryptographic library (versions before 1.7.1). The lc_x509_extract_name_segment() function casts size_t vlen to uint8_t when storing the Common Name (CN) length, potentially leading to overflow and identity impersonation.
Risk Assessment
An attacker can forge a certificate with an identical CN to the victim, enabling impersonation in PKCS#7 verification, certificate chain matching, and code signing.
Recommendation
Update the leancrypto library to version 1.7.1 or later.
Original NVD description (English source)
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.