Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Leancrypto | Leancrypto | < 1.7.1 |
Related Weaknesses (CWE)
References
- https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44Patch
- https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1ProductRelease Notes
- https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4grVendor Advisory
FAQ
What is CVE-2026-34610?
CVE-2026-34610 is a vulnerability with a CVSS score of 5.9 (MEDIUM). 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 uin...
How severe is CVE-2026-34610?
CVE-2026-34610 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-34610?
Check the references section above for vendor advisories and patch information. Affected products include: Leancrypto Leancrypto.