CVE-2026-89102
Received Received - Intake

OCSP Stapling Forgery in wolfSSL Client

Publication date: 2026-09-27

Last updated on: 2026-09-27

Assigner: wolfSSL Inc.

Description
In wolfSSL versions 5.7.2 through 5.9.2 there is a client-side implementation flaw in RFC 6961, multiple OCSP response stapling, which can lead to certificate forgery. When a wolfSSL client enables OCSP stapling with the HAVE_CERTIFICATE_STATUS_REQUEST_V2 feature and calls wolfSSL_UseOCSPStaplingV2(ssl, WOLFSSL_CSR2_OCSP_MULTI, options), the client accepts any certificate in the peer's chain as a certificate authority without verifying that the certificate is actually authorized to act as one. This means that an attacker who possesses any certificate that chains to a CA trusted by the client (along with its private key) can forge certificates for arbitrary identities that will be accepted as valid by the client. The end entity certificate of the server is stored in the persistent trust store, affecting subsequent connections that reuse the context even when OCSP multi usage is not employed. Found by internal wolfSSL testing.

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Meta Information

Published
2026-09-27
Last Modified
2026-09-27
Generated
2026-09-27
AI Q&A
2026-09-27
EPSS Evaluated
N/A
NVD
CVE-2026-89102
EUVD
EUVD-2026-87923

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
wolfssl wolfssl From 5.7.2 (inc) to 5.9.2 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-295 The product does not validate, or incorrectly validates, a certificate.

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Executive Summary

This vulnerability affects wolfSSL versions 5.7.2 through 5.9.2 and involves a client-side flaw in RFC 6961 OCSP response stapling. When OCSP stapling is enabled with HAVE_CERTIFICATE_STATUS_REQUEST_V2, the client fails to verify if a certificate in the peer's chain is authorized to act as a certificate authority. This allows an attacker with any certificate chaining to a trusted CA to forge certificates for arbitrary identities, which the client will accept as valid.

Detection Guidance

To detect this vulnerability, check if your wolfSSL version is between 5.7.2 and 5.9.2 and if OCSP stapling with HAVE_CERTIFICATE_STATUS_REQUEST_V2 is enabled. Inspect the wolfSSL library version and configuration flags. No specific commands are provided in the context.

Impact Analysis

An attacker could impersonate trusted servers or services, leading to man-in-the-middle attacks, data interception, or unauthorized access. The forged certificates may be stored in the persistent trust store, affecting future connections even without OCSP multi usage enabled.

Compliance Impact

This vulnerability allows certificate forgery, which could undermine trust in encrypted communications. For GDPR, it may risk data integrity and confidentiality during transmission. For HIPAA, it could expose protected health information to unauthorized parties if certificates are forged.

Mitigation Strategies

Update wolfSSL to a version that includes the fix for OCSP stapling vulnerabilities, specifically versions addressing the issues in 5.7.2 through 5.9.2. Review and disable OCSP stapling with HAVE_CERTIFICATE_STATUS_REQUEST_V2 if not required. Monitor for any unauthorized certificate usage in your trust store.

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