CVE-2026-5503
9.1 · CRITICALOverview
CVE-2026-5503 is a critical-severity vulnerability affecting wolfssl wolfssl. It was published on April 9, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
In TLSX_EchChangeSNI, the ctx->extensions branch set extensions unconditionally even when TLSX_Find returned NULL. This caused TLSX_UseSNI to attach the attacker-controlled publicName to the shared WOLFSSL_CTX when no inner SNI was configured. TLSX_EchRestoreSNI then failed to clean it up because its removal was gated on serverNameX != NULL. The inner ClientHello was sized before the pollution but written after it, causing TLSX_SNI_Write to memcpy 255 bytes past the allocation boundary.
Remediation
Check the references section for vendor advisories and patches from wolfssl. Update wolfssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| wolfssl | wolfssl | 0 | Affected |
References
Frequently Asked Questions
What is CVE-2026-5503?
CVE-2026-5503 is a critical-severity vulnerability affecting wolfssl wolfssl. It was published on April 9, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
How severe is CVE-2026-5503?
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-5503?
Check the references section for vendor advisories and patches from wolfssl. Update wolfssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-5503?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-5503 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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