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CVE-2026-89102

In wolfSSL versions 5.7.2 through 5.9.2 there is a client-side implementation flaw in RFC 6961…

Risk score
40/100
CVSS
6.5 v3.1
Exploit chance (30 days)
0.2%
Published
27 Sep 2026

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What to know

What it is
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_O…
Affected
Wolfssl
Fix
Apply the vendor's security update; see the linked advisory.
Exploitation
No known exploitation

Story map

Story map: WolfsslTHE FLAWSTHE FIXCVE-2026-89102In wolfSSL versions 5.7.2through 5.9.2 there is aclient-side implementation…CVSS 6.5 · EPSS 0%CVE-2026-89134A certificate with no dNSNameSAN but another SAN typepresent (e.gCVSS 9.1 · EPSS 0%CVE-2026-93302Authentication bypassCVSS 8.2 · EPSS 0%CVE-2026-94418UnderWOLFSSL_SMALL_CERT_VERIFY, ProcessPeerCertParse()…CVSS 7.5 · EPSS 0%FixApply the vendor's securityupdate; see the linked advisory.Who is exposedWolfsslAMBER · PATCH THIS WEEKWolfsslA certificate with no dNSNameSAN but another SAN typepresent (e.g. registeredID oriPAddress) bypassed the SubjectCN dNSName name-constraintcheck. The CN-as-DNS fallbackwas gated on cert->subjectCN…Where it standsNo known exploitationCONNECTS TOSame weaknessCWE-295 (CWE-295)80 other warnings in 30 days →Same productEarlier Wolfssl warnings6 in the last 90 days →
Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

Wolfssl: Amber, patch this week. A certificate with no dNSName SAN but another SAN type present (e.g. registeredID or iPAddress) bypassed the Subject CN dNSName name-constraint check. The CN-as-DNS fallback was gated on cert->subjectCN != NULL && cert->altNames == NULL && !cert->isCA instead of "no dNSName SAN", so an out-of-scope CN was accepted. Th…

The flaws

  • CVE-2026-89102: In wolfSSL versions 5.7.2 through 5.9.2 there is a client-side implementation flaw in RFC 6961… (CVSS 6.5 · EPSS 0%)
  • CVE-2026-89134: A certificate with no dNSName SAN but another SAN type present (e.g (CVSS 9.1 · EPSS 0%)
  • CVE-2026-93302: Authentication bypass (CVSS 8.2 · EPSS 0%)
  • CVE-2026-94418: Under WOLFSSL_SMALL_CERT_VERIFY, ProcessPeerCertParse() runs the certificate signature check… (CVSS 7.5 · EPSS 0%)

The fix

Fix: Apply the vendor's security update; see the linked advisory.

Who is exposed: Wolfssl

Where it stands

  • No known exploitation

Connects to

Why it is Yellow

  • CVSS 6.5 medium

References

Original 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.

Last activity 27 Sep 2026. Patch Forecast updates every hour.