title:  Heap-buffer over-read with WOLFSSL_CALLBACKS
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).
affected:
{
defaultStatus: unaffected
modules: TLS
product: wolfSSL
repo: https://github.com/wolfSSL/wolfssl
vendor: wolfSSL
versions:
lessThanOrEqual: 5.6.5, status: affected, version: 0, versionType: release bundle
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 5.3
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
version: 3.1
]
format: CVSS
scenarios: GENERAL
solutions: 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/
workarounds:   *  Do not build wolfSSL with WOLFSSL_CALLBACKS defined