CVE-2022-3786 in OpenSSL
Summary
by MITRE • 11/01/2022
A buffer overrun can be triggered in X.509 certificate verification, specifically in name constraint checking. Note that this occurs after certificate chain signature verification and requires either a CA to have signed a malicious certificate or for an application to continue certificate verification despite failure to construct a path to a trusted issuer. An attacker can craft a malicious email address in a certificate to 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). In a TLS client, this can be triggered by connecting to a malicious server. In a TLS server, this can be triggered if the server requests client authentication and a malicious client connects.
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Analysis
by VulDB Data Team • 04/14/2026
The vulnerability described in CVE-2022-3786 represents a critical buffer overrun condition within X.509 certificate verification processes, specifically during name constraint checking operations. This flaw exists within the cryptographic certificate validation infrastructure that underpins secure communications across internet protocols. The vulnerability manifests when applications process X.509 certificates containing specially crafted malicious email addresses that exploit improper bounds checking in the name constraint validation logic. The buffer overflow occurs when the system attempts to process certificate subject alternative names containing sequences of the dot character with specific byte patterns that exceed allocated memory boundaries. This issue falls under the CWE-121 category of stack-based buffer overflow, where insufficient bounds checking allows attackers to overwrite adjacent stack memory locations. The vulnerability demonstrates a classic example of improper input validation in cryptographic libraries, where certificate parsing routines fail to adequately sanitize user-provided data during certificate chain validation.
The technical exploitation of this vulnerability requires careful crafting of certificate data to trigger the buffer overrun condition during name constraint processing. Attackers can construct malicious certificates containing specially formatted email addresses where the dot character appears in sequences that cause stack memory corruption when processed by vulnerable verification routines. The specific triggering mechanism involves placing the decimal character 46 (the dot character) in patterns that exceed the allocated buffer space, allowing for arbitrary byte overwrites on the stack. This particular implementation flaw affects both TLS client and server implementations, creating multiple attack vectors depending on the certificate validation context. The vulnerability requires either a certificate authority to have signed a malicious certificate or for applications to continue processing certificates despite path construction failures to trusted issuers, indicating that the flaw operates at a specific stage of certificate validation rather than during initial signature verification. The attack scenario demonstrates how certificate validation logic can become a vector for memory corruption attacks, particularly in systems that perform extensive name constraint checking during certificate chain validation.
The operational impact of this vulnerability extends beyond simple denial of service conditions, presenting significant security risks to systems that rely on proper certificate validation for secure communications. When exploited, the buffer overflow can cause application crashes, leading to service disruption and potential denial of service across affected systems. The vulnerability affects both client and server implementations of TLS protocols, meaning that any system participating in secure communications could be compromised through either malicious server connections or malicious client authentication attempts. In TLS client scenarios, connecting to a malicious server with crafted certificates can trigger the vulnerability, while TLS servers can be compromised when they request client authentication and receive malicious client certificates. This dual attack surface makes the vulnerability particularly concerning for infrastructure components that handle both client and server certificate validation. The vulnerability's impact aligns with ATT&CK technique T1552.001 for credential access and T1499.004 for network denial of service, as it can disrupt secure communication channels and potentially allow attackers to gain unauthorized access to systems through service disruption or memory corruption.
Mitigation strategies for CVE-2022-3786 should focus on immediate patching of affected cryptographic libraries and certificate validation components. Organizations must ensure that all TLS implementations and certificate processing libraries receive updates from vendors to address the specific buffer overrun conditions in name constraint checking. The vulnerability requires careful monitoring of certificate validation routines to prevent continued processing of certificates despite path construction failures, as this behavior can enable exploitation. System administrators should implement certificate pinning mechanisms where appropriate to reduce the impact of malicious certificate generation, while also monitoring for unusual certificate validation patterns that might indicate exploitation attempts. Security teams should conduct thorough vulnerability assessments of all systems handling X.509 certificate validation, particularly those implementing extensive name constraint checking. The fix typically involves implementing proper bounds checking in name constraint validation routines, ensuring that input data is properly sanitized before processing, and adding additional validation steps to prevent buffer overflows during certificate parsing operations. Organizations should also consider implementing intrusion detection systems that can identify unusual certificate processing patterns that might indicate exploitation attempts, as this vulnerability represents a sophisticated attack vector that can be used to disrupt secure communications infrastructure.