CRL check skipped when OCSP enabled and certificate has no OCSP URL
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-94417
- 2026-10-03 Alias added: GHSA-vqr9-9vw2-33w6
References
More Wolfssl vulnerabilities
- TI-2024-00830 SEGV and out of bounds memory read from malicious packet CVSS 3.1CRITICAL 9.1
- TI-2022-18557 In wolfSSL before 5.5.1, malicious clients can cause a buffer overflow during a TLS 1.3… CVSS 3.1HIGH 7.5
- TI-2025-10943 Potential DoS Vulnerability through Multiple KeyShareEntry with Same Group in TLS 1.3 ClientHello CVSS 4.0MEDIUM 6.3
- TI-2017-09737 wolfSSL Bleichenbacher/ROBOT CVSS 3.0HIGH 7.5
- TI-2019-08902 wolfSSL 4.0.0 has a Buffer Overflow in DoPreSharedKeys in tls13.c when a current identity… CVSS 3.1CRITICAL 9.8
- TI-2017-02021 Improper certificate validation in wolfSSL CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-94417 · CVE Program
- CVE-2026-94417 · NVD
- FIRST EPSS
- GHSA-vqr9-9vw2-33w6 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences