Heap-based buffer overflow in wolfSSL - CVE-2026-5503
Published: April 14, 2026
Vulnerability identifier: #VU125932
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-5503
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: wolfSSL
Affected software:
wolfSSL
wolfSSL
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service or execute arbitrary code.
The vulnerability exists due to a heap-based buffer overflow in TLSX_EchChangeSNI and TLSX_SNI_Write when processing ECH SNI state changes. A remote attacker can supply an attacker-controlled publicName to cause a denial of service or execute arbitrary code.
The overflow occurs when no inner SNI is configured.
How to mitigate CVE-2026-5503
Install security update from vendor's website.