AUGUST 4, 2026
Live Feed
Back to database
Case File

CVE-2026-5503

CRITICAL · CVSS 9.1 EPSS 0.39% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2026-04-09 · Last synced 2026-08-04

CyberRota Analysis

This is a critical severity vulnerability with a CVSS score of 9.1. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-5503
Severity
CRITICAL
CVSS
9.1
EPSS
0.39%

Original NVD 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.

Related CVEs

Other vulnerabilities affecting the same vendor(s)