smuellerDD leancrypto up to 1.7.0 lc_x509_extract_name_segment numeric conversion

Summaryinfo

A vulnerability has been found in smuellerDD leancrypto up to 1.7.0 and classified as problematic. The affected element is the function lc_x509_extract_name_segment. Performing a manipulation results in numeric conversion. This vulnerability is reported as CVE-2026-34610. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic has been found in smuellerDD leancrypto up to 1.7.0. This affects the function lc_x509_extract_name_segment. The manipulation with an unknown input leads to a numeric conversion vulnerability. CWE is classifying the issue as CWE-681. When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur. This is going to have an impact on integrity. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-34610 since 03/30/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 1.7.1 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• smuellerDD

Name

• leancrypto

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7.0

License

• open-source

Website

• Product: https://github.com/smuellerDD/leancrypto/

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