wolfSSL 5.9.4 Fixes Eleven TLS and Certificate Validation Flaws
Tech GuruQuick Answer
wolfSSL released 5.9.4 with fixes for eleven CVEs affecting specific TLS, DTLS, certificate-validation, revocation, shutdown, and session-cache configurations through 5.9.2. Inventory exact builds and compile-time options, match each deployment to the vendor's CVE-specific conditions, and move affected systems to 5.9.4 or a supported downstream build containing the applicable fixes.
Confirm Scope And Apply The Supported Fix
What to do now: Locate wolfSSL consumers and embedded copies, record versions and build options, match each use to the eleven CVE-specific conditions, install wolfSSL 5.9.4 or a supported fixed downstream build, recreate persistent contexts and caches where the release requires it, and exercise representative TLS, DTLS, mutual-authentication, OCSP, CRL, and resumption paths.
Last verified: 2026-09-27 UTC. Recheck the authoritative advisory and supported distribution channel before changing production.
Scope And Authority
| Product scope | wolfSSL releases through 5.9.2 under the CVE-specific protocol, API, feature, macro, and cache conditions |
|---|---|
| Advisory | wolfSSL 5.9.4 |
| CVEs | CVE-2026-15442, CVE-2026-89102, CVE-2026-89133, CVE-2026-89134, CVE-2026-89135, CVE-2026-89136, CVE-2026-93302, CVE-2026-93304, CVE-2026-94417, CVE-2026-94418, CVE-2026-94419 |
| Authoritative release date | 2026-09-25 (date stated by wolfSSL in the 5.9.4 release title; GitHub published the release at 2026-09-27 03:55:55 UTC) |
| Authority revision date | GitHub release metadata last updated 2026-09-27 03:57:54 UTC; wolfSSL does not label a separate material advisory revision |
| Affected versions | CVE-specific ranges through wolfSSL 5.9.2; applicability depends on the exact (D)TLS protocol, certificate workflow, API, build macro, callback, revocation, or session-cache conditions in the vendor release. |
| Fixed version | wolfSSL 5.9.4 |
| CVSS base score | 2.3 / 6.3 / 8.3 (CVSS v4.0) |
| CVSS severity | Low to High |
| Exploitation status | Not stated by the authority; no exploitation claim is inferred. |
What Changed
wolfSSL 5.9.4 corrects eleven flaws spanning trusted-peer and certificate validation, OCSP and CRL handling, raw public keys, early ChangeCipherSpec processing, shutdown state, and legacy session-cache references. The vendor rates three High, four Medium, and four Low.
What To Validate Now
- Inventory. Locate direct, statically linked, embedded, appliance, and transitive wolfSSL deployments; record the exact version, package origin, build macros, protocol modes, certificate APIs, revocation settings, verification callbacks, session-cache APIs, and accountable owners.
- Establish applicability. Use the vendor's per-CVE affected ranges and configuration preconditions. A wolfSSL version at or below 5.9.2 is not by itself proof that every listed flaw applies, and a default build is not affected by every item.
- Remediate. Upgrade affected deployments to wolfSSL 5.9.4 or a vendor-supported downstream build that demonstrably contains each applicable fix. If change cannot be immediate, apply only the CVE-specific vendor mitigation; for CVE-2026-93302 the release identifies disabling OpenSSL-compatible defaults and avoiding the trust-peer APIs as a mitigation.
- Validate. Confirm the loaded library and embedded build, rebuild dependent software where required, recreate long-lived WOLFSSL_CTX instances and relevant caches, and test certificate constraints, trusted-peer use, RPK, OCSP/CRL, TLS/DTLS handshakes, shutdown, mutual authentication, and session resumption used in production.
- Retain evidence. Preserve asset and owner identifiers, the applicability decision, before-and-after versions, change approval, installation output, validation results, and any exception or rollback record.
Operational Cautions
Configuration preconditions differ substantially across the eleven CVEs. Replacing a library file may not update statically linked or embedded copies; CVE-2026-94417 and CVE-2026-94418 can leave persistent certificate-manager state, and CVE-2026-94419 changes the cache format. Follow the vendor's restart or cache-handling implications, preserve build provenance, and do not infer exploitation from severity.
Evidence To Retain
- Exact product, release stream, package or application version, enabled feature, environment, and accountable owner.
- UTC timestamps, authority revision, approved change record, installer or package-manager output, and resulting version.
- Relevant logs and monitoring evidence, test results, exceptions, compensating controls, and rollback decisions.
Related TechGeeks Resources
Authoritative References
Correction policy: If the authority changes affected versions, fixed versions, severity, exploitation information, mitigations, or required action, TechGeeks will update this notice and its verification date.
