Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
CWE-599 Variant Incomplete
Missing Validation of OpenSSL Certificate
This vulnerability occurs when an application uses OpenSSL but fails to properly verify server certificates by not calling SSL_get_verify_result(). Without this validation, the application may…
Definition
What is CWE-599?
This vulnerability occurs when an application uses OpenSSL but fails to properly verify server certificates by not calling SSL_get_verify_result(). Without this validation, the application may accept insecure or fraudulent certificates.
When an application connects to a server using OpenSSL, it must explicitly verify that the server's certificate is valid and trustworthy. Skipping the SSL_get_verify_result() function means the application blindly accepts any certificate presented, missing critical checks for expiration, proper signing by a trusted Certificate Authority (CA), hostname matching, and revocation status.
This missing validation creates an open door for attackers to impersonate trusted servers using self-signed, expired, or otherwise invalid certificates. It enables man-in-the-middle (MITM) attacks where encrypted traffic can be intercepted and decrypted, potentially exposing sensitive data like login credentials or API keys that the application transmits.
Real-world impact
Real-world CVEs caused by CWE-599
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 4
Iterate until the response leaks data, executes attacker code, or escalates privileges.
Vulnerable code example
Vulnerable C
The following OpenSSL code ensures that the host has a certificate.
if (cert = SSL_get_peer_certificate(ssl)) {
```
// got certificate, host can be trusted*
*//foo=SSL_get_verify_result(ssl);*
*//if (X509_V_OK==foo) ...*
} Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-599
- Architecture and Design Ensure that proper authentication is included in the system design.
- Implementation Understand and properly implement all checks necessary to ensure the identity of entities involved in encrypted communications.
Detection signals
How to detect CWE-599
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
CWE-599
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Frequently asked questions What is CWE-599?
How serious is CWE-599?
What languages or platforms are affected by CWE-599?
How can I prevent CWE-599?
How does Plexicus detect and fix CWE-599?
Where can I learn more about CWE-599?
Frequently asked questions
What is CWE-599?
This vulnerability occurs when an application uses OpenSSL but fails to properly verify server certificates by not calling SSL_get_verify_result(). Without this validation, the application may accept insecure or fraudulent certificates.
How serious is CWE-599?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-599?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-599?
Ensure that proper authentication is included in the system design. Understand and properly implement all checks necessary to ensure the identity of entities involved in encrypted communications.
How does Plexicus detect and fix CWE-599?
Plexicus's SAST engine matches the data-flow signature for CWE-599 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-599?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/599.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-599
CWE-295 Parent
Improper Certificate Validation
This vulnerability occurs when an application fails to properly verify the authenticity of a digital certificate, or performs the…
CWE-296 Sibling
Improper Following of a Certificate's Chain of Trust
This vulnerability occurs when software fails to properly validate the entire certificate chain back to a trusted root authority. This…
CWE-297 Sibling
Improper Validation of Certificate with Host Mismatch
This vulnerability occurs when an application accepts a valid SSL/TLS certificate without properly verifying that it actually belongs to…
CWE-298 Sibling
Improper Validation of Certificate Expiration
This vulnerability occurs when an application fails to properly check if a digital certificate has expired, potentially trusting…
CWE-299 Sibling
Improper Check for Certificate Revocation
This vulnerability occurs when an application fails to properly verify whether a security certificate has been revoked, potentially…
Ready to validate what matters?
Ready to validate what matters?
Plexicus is Proof-Driven AppSec: validated findings, contextual understanding, and reviewed remediation — anchored in evidence, scoped with you.