Cyber Resilience

CVE-2026-34610

Leancrypto ≤ 1.7.1

Published
02 April 2026
Modified
24 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 5.9
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS Score 0.0016 6th percentile
Risk Priority 44 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-34610 is a medium-severity Incorrect Conversion between Numeric Types (CWE-681) vulnerability in Leancrypto Leancrypto. Its CVSS base score is 5.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

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 =…

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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.

CWE(s)
CWE-681

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-24884Shared CWE-681
CVE-2026-53133Shared CWE-681
CVE-2024-32481Shared CWE-681
CVE-2024-7747Shared CWE-681
CVE-2024-1552Shared CWE-681
CVE-2026-4602Shared CWE-681
CVE-2023-21736Shared CWE-681
CVE-2026-9143Shared CWE-681
CVE-2023-23388Shared CWE-681
CVE-2026-4931Shared CWE-681

Affected Assets

leancrypto
leancrypto
≤ 1.7.1

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover incorrect numeric conversions through targeted test cases.

SA-8 Security and Privacy Engineering Principles partial match

Engineering principles can mandate safe numeric handling and range checks that structurally avoid bad conversions.

SI-10 Information Input Validation partial match

Input validation directly stops malformed or out-of-range numeric values from reaching conversion logic.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require code reviews, static analysis, and developer training that catch and prevent numeric type-conversion errors.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect numeric conversion defects before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle includes type-safety and conversion checks that reduce numeric truncation risks.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate safe numeric handling and range validation.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles promote strong typing and safe conversion practices.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly address correct numeric type conversions and overflow checks.

References