Partial-Chain Certificate Verification Flaw in wolfSSL
CVE-2026-6091

6MEDIUM

Key Information:

Vendor

Wolfssl

Status
Wolfssl
Vendor
CVE Published:
25 June 2026

What is CVE-2026-6091?

The vulnerability in wolfSSL arises from a flaw in the partial-chain certificate verification process, which may improperly accept certificate chains ending in an untrusted intermediate certificate supplied by a malicious peer. This flaw could allow an attacker to present a certificate chain terminating at an intermediate they control, circumventing normal trust mechanisms. It specifically affects the X509 verification functions when the X509_V_FLAG_PARTIAL_CHAIN flag is used. Users are advised to apply the latest security patches to mitigate this risk.

Affected Version(s)

wolfSSL 5.7.4 <= 5.9.1

References

https://github.com/wolfSSL/wolfssl/pull/10170
patch
https://www.wolfssl.com/docs/security-vulnerabilities/

CVSS V4

Score:
6
Severity:
MEDIUM
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Dikai Zou
.