Stack Buffer Over-read in wolfSSL MatchDomainName Causes Crash

Publication date: 2026-04-09

Last updated on: 2026-04-29

Assigner: wolfSSL Inc.

Description

A 1-byte stack buffer over-read was identified in the MatchDomainName function (src/internal.c) during wildcard hostname validation when the LEFT_MOST_WILDCARD_ONLY flag is active. If a wildcard * exhausts the entire hostname string, the function reads one byte past the buffer without a bounds check, which could cause a crash.

CVSS Scores

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Meta Information

Published

2026-04-09

Last Modified

2026-04-29

Generated

2026-07-06

AI Q&A

2026-04-10

EPSS Evaluated

2026-07-05

NVD

CVE-2026-5772

EUVD

EUVD-2026-21218

Affected Vendors & Products

Vendor	Product	Version / Range
wolfssl	wolfssl	to 5.9.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-126	The product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer.

Attack-Flow Graph

Executive Summary

This vulnerability is a 1-byte stack buffer over-read found in the MatchDomainName function within the source code file src/internal.c. It occurs during the validation of wildcard hostnames when the LEFT_MOST_WILDCARD_ONLY flag is enabled. Specifically, if a wildcard character (*) matches the entire hostname string, the function reads one byte beyond the allocated buffer without checking boundaries, which can lead to a program crash.

Impact Analysis

The primary impact of this vulnerability is that it can cause the affected software to crash due to reading memory beyond the intended buffer. This could lead to denial of service if the software is critical to operations. There is no indication from the provided information that this vulnerability allows for code execution or data leakage.

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