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wolfSSL EUVDEUVD-2026-87908

| CVE-2026-94417 LOW
Improper Check for Certificate Revocation (CWE-299)
2026-09-27 wolfSSL GHSA-vqr9-9vw2-33w6
2.3
CVSS 4.0 · Vendor: wolfSSL

Severity by source

Vendor (wolfSSL) PRIMARY
2.3 LOW
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
4.2 MEDIUM

AC:H because both revocation methods must be configured and the cert must lack an OCSP URL while being CRL-revoked; PR:L reflects the attacker having held a CA-issued (now-revoked) cert; C:L/I:L for MITM/impersonation potential.

3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
4.0 AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (wolfSSL).

CVSS VectorVendor: wolfSSL

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

1
Analysis Generated
Sep 27, 2026 - 09:47 vuln.today

DescriptionCVE.org

When an application enables both OCSP and CRL revocation checking on one WOLFSSL_CTX or certificate manager, wolfSSL skips the CRL check for any peer certificate that carries no Authority Information Access OCSP URL, and accepts a certificate the loaded CRL lists as revoked. The soft-fail policy for a missing responder collapses the OCSP result onto success before the code decides whether the CRL fallback is still needed, so "no responder exists" becomes indistinguishable from "the responder answered good". Affected builds define both HAVE_OCSP and HAVE_CRL: --enable-ocsp --enable-crl directly, and implicitly --enable-all, --enable-distro, --enable-curl, --enable-nginx, --enable-haproxy, --enable-stunnel, --enable-lighty, --enable-wpas, --enable-strongswan, --enable-mosquitto, --enable-jni, --enable-openvpn and --enable-krb. An application is affected only if it calls both wolfSSL_CTX_EnableOCSP() (or wolfSSL_EnableOCSP() / wolfSSL_CertManagerEnableOCSP()) and wolfSSL_CTX_EnableCRL() (or the equivalents) with a CRL loaded; an application that uses OCSP stapling alone through wolfSSL_CTX_EnableOCSPStapling() is not affected, because that sets up a separate OCSP instance. The defect sits in ProcessPeerCerts() and is reachable over TLS 1.0 through TLS 1.3 and DTLS, both on a client verifying a server certificate and on a server verifying a client certificate under mutual or post-handshake authentication. When the skipped check falls on a chain certificate rather than the leaf, the unchecked intermediate is promoted into the certificate manager and stays a trusted signer for every later connection on that context, so an affected long-running process needs its WOLFSSL_CTX torn down and not only its library replaced. All wolfSSL versions from 5.9.2 and earlier are affected; on versions 5.9.1 and 5.9.2 the WOLFSSL_OCSP_CHECKALL configuration fails closed with OCSP_NEED_URL, which leaves wolfSSL_CTX_EnableOCSP() without CHECKALL as the exposed configuration on 5.9.2.

AnalysisAI

Certificate revocation checking in wolfSSL builds that enable both OCSP and CRL can be silently bypassed, allowing a certificate that the loaded CRL explicitly lists as revoked to be accepted during a TLS/DTLS handshake. Only applications that define both HAVE_OCSP and HAVE_CRL (for example --enable-ocsp --enable-crl, or bundles such as --enable-all, --enable-nginx, --enable-haproxy, --enable-openvpn, --enable-strongswan) and that actually call both wolfSSL_CTX_EnableOCSP() and wolfSSL_CTX_EnableCRL() with a CRL loaded are exposed; OCSP-stapling-only applications are not affected. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

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Vulnerability AssessmentAI

Exploitation Requires a wolfSSL build defining BOTH HAVE_OCSP and HAVE_CRL - via --enable-ocsp --enable-crl or bundles such as --enable-all, --enable-distro, --enable-nginx, --enable-haproxy, --enable-stunnel, --enable-openvpn, --enable-strongswan, --enable-mosquitto, etc. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment All signals point to a genuinely LOW real-world priority despite the security-critical nature of a revocation bypass. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Upstream fix available (PR/commit); released patched version not independently confirmed. … Detailed patch versions, workarounds, and compensating controls in full report.

Threat intelligence, references, and detailed analysis are available after sign-in.

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EUVD-2026-87908 vulnerability details – vuln.today

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