CVE-2026-5503

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.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/wolfSSL/wolfssl/pull/10102	Issue Tracking

Configurations

Configuration 1 (hide)

cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*

History

27 Apr 2026, 17:53

Type	Values Removed	Values Added
References	~~() https://github.com/wolfSSL/wolfssl/pull/10102 -~~	() https://github.com/wolfSSL/wolfssl/pull/10102 - Issue Tracking
First Time		Wolfssl Wolfssl wolfssl
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.1
CPE		cpe:2.3:a:wolfssl:wolfssl::::::::

09 Apr 2026, 23:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-09 23:17

Updated : 2026-04-27 17:53

NVD link : CVE-2026-5503

Mitre link : CVE-2026-5503

CVE.ORG link : CVE-2026-5503

JSON object : View

Products Affected

wolfssl

wolfssl

CWE

CWE-787

Out-of-bounds Write

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