CWE-784: Reliance on Cookies without Validation and Integrity Checking in a Security Decision

Code Examples & CVEs

Demonstrative Examples

The following code excerpt reads a value from a browser cookie to determine the role of the user.

BadJava

Cookie[] cookies = request.getCookies();for (int i =0; i< cookies.length; i++) {Cookie c = cookies[i];if (c.getName().equals("role")) {userRole = c.getValue();}}

The following code could be for a medical records application. It performs authentication by checking if a cookie has been set.

The programmer expects that the AuthenticateUser() check will always be applied, and the "authenticated" cookie will only be set when authentication succeeds. The programmer even diligently specifies a 2-hour expiration for the cookie.

BadPHP

$auth = $_COOKIES['authenticated'];if (! $auth) {if (AuthenticateUser($_POST['user'], $_POST['password']) == "success") {// save the cookie to send out in future responsessetcookie("authenticated", "1", time()+60*60*2);}else {ShowLoginScreen();die("\n");}}DisplayMedicalHistory($_POST['patient_ID']);

In the following example, an authentication flag is read from a browser cookie, thus allowing for external control of user state data.

BadJava

Cookie[] cookies = request.getCookies();for (int i =0; i< cookies.length; i++) {Cookie c = cookies[i];if (c.getName().equals("authenticated") && Boolean.TRUE.equals(c.getValue())) {authenticated = true;}}

Observed CVE Examples (5)

CVE-2009-1549

Attacker can bypass authentication by setting a cookie to a specific value.

View Details

CVE-2009-1619

Attacker can bypass authentication and gain admin privileges by setting an "admin" cookie to 1.

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CVE-2009-0864

Content management system allows admin privileges by setting a "login" cookie to "OK."

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CVE-2008-5784

e-dating application allows admin privileges by setting the admin cookie to 1.

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CVE-2008-6291

Web-based email list manager allows attackers to gain admin privileges by setting a login cookie to "admin."

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-784 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-784, Reliance on Cookies without Validation and Integrity Checking in a Security Decision, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Reliance on Cookies without Validation and Integrity Checking in a Security Decision during Architecture and Design

MITRE associates mitigation with Architecture and Design, and Implementation; recorded impacts include Bypass Protection Mechanism, and Gain Privileges or Assume Identity; observed examples include CVE-2009-1549, CVE-2009-1619, and CVE-2009-0864. Use these source-defined anchors to turn CWE-784 into implementation, review, and verification checks for the affected component.

CWE-784: Reliance on Cookies without Validation and Integrity Checking in a Security Decision — MITRE CWE

Triage CWE-784 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-784, Reliance on Cookies without Validation and Integrity Checking in a Security Decision, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-784

Apply MITRE's full root-cause mapping guidance when using CWE-784, Reliance on Cookies without Validation and Integrity Checking in a Security Decision. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-784 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-784, Reliance on Cookies without Validation and Integrity Checking in a Security Decision. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-784: Reliance on Cookies without Validation and Integrity Checking in a Security Decision?+

CWE-784: Reliance on Cookies without Validation and Integrity Checking in a Security Decision is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product uses a protection mechanism that relies on the existence or values of a cookie, but it does not properly ensure that the cookie is valid for the associated user. Attackers can easily modify cookies, within the browser or by implementing the client-side code outside of the browser. Attackers can bypass protection mechanisms such as authorization and authentication by modifying the cookie to contain an expected value.

What are the security consequences of Reliance on Cookies without Validation and Integrity Checking in a Security Decision?+

If exploited, CWE-784 (Reliance on Cookies without Validation and Integrity Checking in a Security Decision) it can compromise Access Control, leading to outcomes such as Bypass Protection Mechanism and Gain Privileges or Assume Identity.

How do you prevent or mitigate Reliance on Cookies without Validation and Integrity Checking in a Security Decision?+

Recommended mitigations for CWE-784 include: Avoid using cookie data for a security-related decision. Perform thorough input validation (i.e.: server side validation) on the cookie data if you're going to use it for a security related decision. Add integrity checks to detect tampering.

Which programming languages are affected by Reliance on Cookies without Validation and Integrity Checking in a Security Decision?+

CWE-784 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Reliance on Cookies without Validation and Integrity Checking in a Security Decision?+

MITRE documents real CVEs mapped to CWE-784, including CVE-2009-1549, CVE-2009-1619, CVE-2009-0864, CVE-2008-5784 and CVE-2008-6291. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-784 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-784: Reliance on Cookies without Validation and Integrity Checking in a Security Decision

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Detection Methods

Code Examples & CVEs

Demonstrative Examples

Observed CVE Examples (5)

CWE Relationships

Parent Weaknesses

Source-backed guidance

Verify controls for CWE-784 with SSDF evidence

Address Reliance on Cookies without Validation and Integrity Checking in a Security Decision during Architecture and Design

Triage CWE-784 against known exploitation evidence

Apply precise root-cause mapping to CWE-784

Validate CWE-784 with root-cause mapping checks

Frequently Asked Questions

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