CVE-2026-34610
leancrypto: Integer truncation in X.509 name parser enables certificate identity impersonation
- State
- Published
- Severity
- 5.9 Medium
- Published
- Apr 2, 2026
- Updated
- Apr 3, 2026
- Reserved
- Mar 30, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.9 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N | GitHub_M |
Weaknesses
- CWE-681 Incorrect Conversion between Numeric Types
Affected Products
| Product | Versions |
|---|---|
leancryptosmuellerDD |
|
References
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