Vulnerability record · CVE-2022-3786 · published 1 November 2022
CVE-2022-3786: OpenSSL X.509 name constraint buffer overrun causes denial of service
OOpenssl · Openssl
OpenSSL's X.509 certificate verification contains a stack buffer overrun in name constraint checking. A malicious certificate can embed an email address with an arbitrary number of '.' characters, overflowing the stack after chain signature verification. This can crash the process, causing a denial of service.
Description
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Automated analysis
high priorityCVSS 7.5 with network reachability and no authentication, plus a very high EPSS score, though impact is limited to denial of service and no KEV listing.
What it is
OpenSSL's X.509 certificate verification contains a stack buffer overrun in name constraint checking. A malicious certificate can embed an email address with an arbitrary number of '.' characters, overflowing the stack after chain signature verification. This can crash the process, causing a denial of service.
Impact
An attacker can crash the affected process, causing a denial of service. The CVSS vector shows no confidentiality or integrity impact, only availability (A:H).
Attack surface
Reachable over the network without authentication or user interaction (AV:N/AC:L/PR:N/UI:N). In a TLS client it triggers when connecting to a malicious server; in a TLS server it triggers when the server requests client authentication and a malicious client connects.
Exploitation
Not listed in CISA KEV and no ransomware use documented. EPSS is very high (0.92488, 99.82nd percentile), and references include a vendor patch and advisories, indicating active attention but no confirmed in-the-wild exploitation in this record.
What to do
- Apply the OpenSSL patch referenced in the vendor advisory (commit c42165b5706e42f67ef8ef4c351a9a4c5d21639a) or upgrade to a fixed OpenSSL release.
- Update dependent products listed (Fedora, Node.js) to versions that bundle the fixed OpenSSL.
- Where immediate patching is not possible, avoid or restrict TLS client authentication and untrusted server connections.
- Monitor vendor advisories from Intel, Siemens and CERT/CC for product-specific fixes.
Detection
- Monitor for process crashes or abnormal termination in services using OpenSSL during TLS handshakes.
- Inspect TLS certificate chains for email addresses containing unusually long runs of '.' characters.
- Correlate crash telemetry with inbound TLS connections from untrusted sources, especially when client authentication is requested.
This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.
Affected products
3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.
References
Track CVE-2022-3786 inside VULONE
Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.
Related vulnerabilities
Same products first, then exploited flaws of the same weakness class.
Source: NIST National Vulnerability Database (record CVE-2022-3786), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.
