# CVE-2026-34610

## Summary

- **CVE ID:** CVE-2026-34610
- **Severity:** MEDIUM
- **CVSS Score:** 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N)
- **CWE:** CWE-681
- **Published:** Apr 2, 2026
- **Last Modified:** Apr 3, 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.

## Affected Products

- smuellerDD — leancrypto (< 1.7.1)

## References

- [CNA](https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4gr)
- [CNA](https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a)
- [CNA](https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.16%
- **EPSS Percentile:** 5.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._