CVE-2023-6936

Heap-buffer over-read with WOLFSSL_CALLBACKS

Published Feb 20, 2024 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
In wolfSSL prior to 5.6.6, if callback functions are enabled (via the WOLFSSL_CALLBACKS flag), then a malicious TLS client or network attacker can trigger a buffer over-read on the heap of 5 bytes (WOLFSSL_CALLBACKS is only intended for debugging).

Remediation

Vendor Solution

The fix for this issue is located in the following GitHub Pull Request: https://github.com/wolfSSL/wolfssl/pull/6949/ https://github.com/wolfSSL/wolfssl/pull/6949/


Vendor Workaround

* Do not build wolfSSL with WOLFSSL_CALLBACKS defined

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2023-59134 In wolfSSL prior to 5.6.6, if callback functions are enabled (via the WOLFSSL_CALLBACKS flag), then a malicious TLS client or network attacker can trigger a buffer over-read on the heap of 5 bytes (WOLFSSL_CALLBACKS is only intended for debugging).
History
Type Values Removed Values Added
Metrics epss

{'score': 0.00187}

epss

{'score': 0.00255}

Type Values Removed Values Added
Weaknesses CWE-126
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Wolfssl
Wolfssl wolfssl
Weaknesses CWE-125
CPEs cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*
Vendors & Products Wolfssl
Wolfssl wolfssl
Weaknesses

Sources

Status
PUBLISHED
Assigner
wolfSSL
Published
Updated
Mar 26, 2025, 4:28 PM
Reserved
Dec 18, 2023, 10:01 PM
Status
Modified
Published
Feb 20, 2024, 10:15 PM
Modified
Jun 17, 2026, 6:51 AM