CWE-296 Base Draft Low likelihood

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 mistake can cause the system to incorrectly trust a certificate…

Definition

What is CWE-296?

This vulnerability occurs when software fails to properly validate the entire certificate chain back to a trusted root authority. This mistake can cause the system to incorrectly trust a certificate and the resource it represents, creating a security gap.
A certificate's trustworthiness isn't inherent; it's derived from a verifiable chain linking it back to a root certificate you already trust. If your code only checks the first link—or skips any intermediate certificates—you haven't actually verified the chain. This is like trusting an ID card because it looks official, without checking if the issuing authority is legitimate and properly authorized the person who issued it. The chain can break in several common ways. These include accepting a self-signed certificate (unless it's the designated root), failing to validate every intermediate certificate's constraints and signatures, or relying on a root certificate that has been compromised. Each skipped check creates an opportunity for an attacker to present a fraudulent certificate that your software will incorrectly accept as valid.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-296

  • CVE-2016-2402

    Server allows bypass of certificate pinning by sending a chain of trust that includes a trusted CA that is not pinned.

  • CVE-2008-4989

    Verification function trusts certificate chains in which the last certificate is self-signed.

  • CVE-2012-5821

    Chain: Web browser uses a TLS-related function incorrectly, preventing it from verifying that a server's certificate is signed by a trusted certification authority (CA).

  • CVE-2009-3046

    Web browser does not check if any intermediate certificates are revoked.

  • CVE-2009-0265

    chain: DNS server does not correctly check return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.

  • CVE-2009-0124

    chain: incorrect check of return value from the OpenSSL EVP_VerifyFinal function allows bypass of validation of the certificate chain.

  • CVE-2002-0970

    File-transfer software does not validate Basic Constraints of an intermediate CA-signed certificate.

  • CVE-2002-0862

    Cryptographic API, as used in web browsers, mail clients, and other software, does not properly validate Basic Constraints.

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    Identifiziere einen Codepfad, der nicht vertrauenswürdige Eingaben ohne Validierung verarbeitet.

  2. 2

    Erzeuge eine Payload, die das unsichere Verhalten auslöst — Injection, Traversal, Overflow oder Logik-Missbrauch.

  3. 3

    Liefere die Payload über einen normalen Request aus und beobachte die Reaktion der Anwendung.

  4. 4

    Iteriere, bis die Antwort Daten preisgibt, Angreifer-Code ausführt oder Berechtigungen eskaliert.

Verwundbares Codebeispiel

Vulnerable C

This code checks the certificate of a connected peer.

Verwundbar C 
if ((cert = SSL_get_peer_certificate(ssl)) && host)
  	foo=SSL_get_verify_result(ssl);
  if ((X509_V_OK==foo) || X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN==foo))
```
// certificate looks good, host can be trusted*
Sicheres Codebeispiel

Secure pseudo

Sicher 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.
Präventions-Checkliste

How to prevent CWE-296

  • Architecture and Design Ensure that proper certificate checking is included in the system design.
  • Implementation Understand, and properly implement all checks necessary to ensure the integrity of certificate trust integrity.
  • Implementation If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the full chain of trust.
Erkennungssignale

How to detect CWE-296

Automated Static Analysis High

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Plexicus Auto-Fix

Plexicus erkennt CWE-296 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.

Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.

Demo anfordern Plexicus kostenlos testen
Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-296?

This vulnerability occurs when software fails to properly validate the entire certificate chain back to a trusted root authority. This mistake can cause the system to incorrectly trust a certificate and the resource it represents, creating a security gap.

Wie gravierend ist CWE-296?

MITRE stuft die Exploit-Wahrscheinlichkeit als niedrig ein — eine Ausnutzung ist selten, die Schwachstelle sollte aber dennoch behoben werden, sobald sie entdeckt wird.

Welche Sprachen oder Plattformen sind von CWE-296 betroffen?

MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.

Wie kann ich CWE-296 verhindern?

Ensure that proper certificate checking is included in the system design. Understand, and properly implement all checks necessary to ensure the integrity of certificate trust integrity.

Wie erkennt und behebt Plexicus CWE-296?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-296 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.

Wo erfahre ich mehr über CWE-296?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/296.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-296

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-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…

CWE-599 Sibling

Missing Validation of OpenSSL Certificate

This vulnerability occurs when an application uses OpenSSL but fails to properly verify server certificates by not calling…

Ressourcen

Further reading

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