CWE-593 Variant Draft

Authentication Bypass: OpenSSL CTX Object Modified after SSL Objects are Created

This vulnerability occurs when an application modifies an OpenSSL context object after it has already been used to create active SSL/TLS connections.

Definition

What is CWE-593?

This vulnerability occurs when an application modifies an OpenSSL context object after it has already been used to create active SSL/TLS connections.
In OpenSSL, the SSL_CTX object acts as a template for creating individual SSL connection objects. When you change settings in the SSL_CTX after SSL objects have already been instantiated from it, those existing connections may unexpectedly inherit the new configuration. This can lead to inconsistent security states across your application's connections. For developers, this means that security-critical modifications—like changing authentication modes, cipher suites, or certificate settings—should be applied to the SSL_CTX before creating any SSL objects. Once connections are established, altering the parent context introduces unpredictable behavior and can potentially weaken or bypass authentication controls for previously created sessions.
Real-world impact

Real-world CVEs caused by CWE-593

No public CVE references are linked to this CWE in MITRE's catalog yet.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable C

The following example demonstrates the weakness.

Vulnerable C 
#define CERT "secret.pem"
  #define CERT2 "secret2.pem"
  int main(){
  		SSL_CTX *ctx;
  		SSL *ssl;
  		init_OpenSSL();
  		seed_prng();
  		ctx = SSL_CTX_new(SSLv23_method());
  		if (SSL_CTX_use_certificate_chain_file(ctx, CERT) != 1)
  			int_error("Error loading certificate from file");
  		if (SSL_CTX_use_PrivateKey_file(ctx, CERT, SSL_FILETYPE_PEM) != 1)
  			int_error("Error loading private key from file");
  		if (!(ssl = SSL_new(ctx)))
  			int_error("Error creating an SSL context");
  		if ( SSL_CTX_set_default_passwd_cb(ctx, "new default password" != 1))
  			int_error("Doing something which is dangerous to do anyways");
  		if (!(ssl2 = SSL_new(ctx)))
  			int_error("Error creating an SSL context");
  }
Secure code example

Secure pseudo

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-593

  • Architecture and Design Use a language or a library that provides a cryptography framework at a higher level of abstraction.
  • Implementation Most SSL_CTX functions have SSL counterparts that act on SSL-type objects.
  • Implementation Applications should set up an SSL_CTX completely, before creating SSL objects from it.
Detection signals

How to detect CWE-593

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

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Frequently asked questions

Frequently asked questions

What is CWE-593?

This vulnerability occurs when an application modifies an OpenSSL context object after it has already been used to create active SSL/TLS connections.

How serious is CWE-593?

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-593?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-593?

Use a language or a library that provides a cryptography framework at a higher level of abstraction. Most SSL_CTX functions have SSL counterparts that act on SSL-type objects.

How does Plexicus detect and fix CWE-593?

Plexicus's SAST engine matches the data-flow signature for CWE-593 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-593?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/593.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-593

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CWE-415 Sibling

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CWE-605 Sibling

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CWE-672 Sibling

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Resources

Further reading

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