CVE-2022-3786: OpenSSL Buffer Overflow Vulnerability

CVE-2022-3786 Overview

CVE-2022-3786 is a buffer overrun vulnerability in OpenSSL's X.509 certificate verification process, specifically occurring during name constraint checking. The flaw allows an attacker to craft a malicious email address in a certificate that can overflow an arbitrary number of bytes containing the . character (decimal 46) on the stack. This buffer overflow could result in a crash, causing a denial of service condition.

The vulnerability occurs after certificate chain signature verification and requires either a Certificate Authority (CA) to have signed a malicious certificate, or for an application to continue certificate verification despite failing to construct a path to a trusted issuer. In TLS client scenarios, this can be triggered by connecting to a malicious server. In TLS server scenarios, this can be triggered when the server requests client authentication and a malicious client connects.

Critical Impact

This buffer overflow vulnerability in OpenSSL's X.509 certificate verification can cause denial of service through application crashes, affecting both TLS clients and servers across multiple platforms.

Affected Products

• OpenSSL (versions 3.0.0 to 3.0.6)
• Fedora Project Fedora 36 and 37
• Node.js (multiple versions including 18.12.0 LTS and 19.0.0)

Discovery Timeline

• 2022-11-01 - CVE-2022-3786 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2022-3786

Vulnerability Analysis

This vulnerability is classified as a Classic Buffer Overflow (CWE-120) affecting OpenSSL's X.509 certificate name constraint checking functionality. The flaw exists in the certificate verification code path that processes email address constraints within X.509 certificates.

When OpenSSL processes a certificate containing a specially crafted email address in the name constraints extension, it fails to properly validate the length of the input data before copying it to a stack-based buffer. The attacker-controlled overflow is limited to the . character (ASCII decimal 46), which constrains the exploitation potential but still enables reliable denial of service attacks.

The vulnerability is network-accessible without requiring any privileges or user interaction, making it exploitable in automated attack scenarios. However, since the overflow is limited to a single character value, achieving remote code execution is highly unlikely on most platforms, limiting the practical impact to availability compromise.

Root Cause

The root cause of CVE-2022-3786 lies in improper bounds checking within OpenSSL's name constraint verification code. When processing email address fields in X.509 certificates, the code does not adequately validate the length of the email address string before performing memory operations. This allows a maliciously crafted certificate with an excessively long email address to overflow a stack buffer during the name constraint checking process. The overflow is constrained to repeating . characters due to the specific code path and string processing logic involved.

Attack Vector

The attack vector is network-based and can be exploited in two primary scenarios:

TLS Client Attack: An attacker operates a malicious TLS server presenting a certificate with a crafted email address. When a vulnerable TLS client connects and attempts to verify the certificate, the buffer overflow is triggered, causing the client application to crash.

TLS Server Attack: An attacker acts as a malicious TLS client connecting to a server that has client certificate authentication enabled. The attacker presents a malicious client certificate containing the crafted email address, triggering the overflow when the server verifies the certificate.

The vulnerability requires the malicious certificate to either be signed by a trusted CA or for the application to continue certificate processing despite path validation failures. The attack results in a stack buffer overflow with . characters, leading to application crash and denial of service.

Detection Methods for CVE-2022-3786

Indicators of Compromise

• Unexpected application crashes in services using OpenSSL 3.0.x for TLS connections
• Segmentation faults or stack corruption errors in logs from OpenSSL-dependent applications
• Anomalous X.509 certificates with unusually long email address fields in name constraints
• TLS connection failures accompanied by process termination in client or server applications

Detection Strategies

• Monitor application logs for repeated crashes during TLS handshake or certificate verification phases
• Implement network-level inspection for X.509 certificates containing abnormally long email addresses (exceeding typical RFC limits)
• Deploy endpoint detection rules to identify OpenSSL library versions between 3.0.0 and 3.0.6
• Use SentinelOne's behavioral AI to detect anomalous crash patterns indicative of exploitation attempts

Monitoring Recommendations

• Enable enhanced logging for certificate verification failures in TLS-enabled applications
• Implement alerting for service restarts and crash events in critical infrastructure using OpenSSL
• Monitor certificate transparency logs for suspicious certificates issued with unusual name constraints
• Deploy network sensors to inspect and alert on malformed X.509 certificate structures

How to Mitigate CVE-2022-3786

Immediate Actions Required

• Upgrade OpenSSL to version 3.0.7 or later immediately on all affected systems
• Update Node.js to patched versions that include the OpenSSL fix
• Apply Fedora security updates for systems running Fedora 36 or 37
• Audit systems to identify all applications and services using vulnerable OpenSSL 3.0.x versions

Patch Information

OpenSSL has released version 3.0.7 which addresses this vulnerability. The fix is available in the OpenSSL Commit Diff. Detailed information about the vulnerability and remediation is provided in the OpenSSL Security Advisory.

Additional vendor resources include the Intel Security Advisory SA-00789 and CERT Vulnerability Report #794340 for comprehensive mitigation guidance.

Workarounds

• Disable client certificate authentication on TLS servers if not strictly required until patching is complete
• Implement network-level certificate inspection to block certificates with anomalous name constraint fields
• Configure application-level certificate pinning to reduce exposure to malicious certificates from untrusted CAs
• Isolate critical services using vulnerable OpenSSL versions behind additional network security controls

# Verify OpenSSL version and upgrade if vulnerable
openssl version
# If version is 3.0.0-3.0.6, upgrade to 3.0.7+
# On Debian/Ubuntu-based systems:
sudo apt update && sudo apt install openssl

# On RHEL/CentOS/Fedora systems:
sudo dnf update openssl

# Verify upgrade was successful
openssl version