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HIGH · 8.1

CVE-2026-5501

wolfSSL_X509_verify_cert in the OpenSSL compatibility layer accepts a certificate chain in which the leaf's signature is not checked, if the attacker supplies an untrusted intermediate with Basic Cons...

Vulnerability Description

wolfSSL_X509_verify_cert in the OpenSSL compatibility layer accepts a certificate chain in which the leaf's signature is not checked, if the attacker supplies an untrusted intermediate with Basic Constraints `CA:FALSE` that is legitimately signed by a trusted root. An attacker who obtains any leaf certificate from a trusted CA (e.g. a free DV cert from Let's Encrypt) can forge a certificate for any subject name with any public key and arbitrary signature bytes, and the function returns `WOLFSSL_SUCCESS` / `X509_V_OK`. The native wolfSSL TLS handshake path (`ProcessPeerCerts`) is not susceptible and the issue is limited to applications using the OpenSSL compatibility API directly, which would include integrations of wolfSSL into nginx and haproxy.

CVSS Score

8.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE

Affected Products

VendorProductVersions
WolfsslWolfssl<= 5.9.0

Related Weaknesses (CWE)

CWE-295

References

FAQ

What is CVE-2026-5501?

CVE-2026-5501 is a vulnerability with a CVSS score of 8.1 (HIGH). wolfSSL_X509_verify_cert in the OpenSSL compatibility layer accepts a certificate chain in which the leaf's signature is not checked, if the attacker supplies an untrusted intermediate with Basic Cons...

How severe is CVE-2026-5501?

CVE-2026-5501 has been rated HIGH with a CVSS base score of 8.1/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-5501?

Check the references section above for vendor advisories and patch information. Affected products include: Wolfssl Wolfssl.