CWE-804: Guessable CAPTCHA

Extended Description

An automated attacker could bypass the intended protection of the CAPTCHA challenge and perform actions at a higher frequency than humanly possible, such as launching spam attacks. There can be several different causes of a guessable CAPTCHA: An audio or visual image that does not have sufficient distortion from the unobfuscated source image. A question is generated with a format that can be automatically recognized, such as a math question. A question for which the number of possible answers is limited, such as birth years or favorite sports teams. A general-knowledge or trivia question for which the answer can be accessed using a data base, such as country capitals or popular entertainers. Other data associated with the CAPTCHA may provide hints about its contents, such as an image whose filename contains the word that is used in the CAPTCHA.

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-804 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-804, Guessable CAPTCHA, 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

Make elimination of CWE-804 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-804, Guessable CAPTCHA. Put the weakness in the product threat model and security roadmap, fund class-level design and platform changes, prefer safe defaults and reusable guardrails, and publish measurable progress. Do not transfer the primary burden to customer configuration when the manufacturer can remove or contain the root cause in the product.

Shifting the Balance of Cybersecurity Risk: Secure by Design Software — Cybersecurity and Infrastructure Security Agency

Connect Guessable CAPTCHA to documented attack evidence

Recorded impacts include Bypass Protection Mechanism, and Other; observed examples include CVE-2022-4036; related weaknesses include CWE-863, and CWE-1390. Use these source-defined anchors to turn CWE-804 into implementation, review, and verification checks for the affected component.

CWE-804: Guessable CAPTCHA — MITRE CWE

Apply precise root-cause mapping to CWE-804

Apply MITRE's full root-cause mapping guidance when using CWE-804, Guessable CAPTCHA. 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-804 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-804, Guessable CAPTCHA. 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-804: Guessable CAPTCHA?+

CWE-804: Guessable CAPTCHA is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product uses a CAPTCHA challenge, but the challenge can be guessed or automatically recognized by a non-human actor. An automated attacker could bypass the intended protection of the CAPTCHA challenge and perform actions at a higher frequency than humanly possible, such as launching spam attacks. There can be several different causes of a guessable CAPTCHA: An audio or visual image that does not have sufficient distortion from the unobfuscated source image. A question is generated with a format that can be automatically recognized, such as a math question. A question for which the number of possible answers is limited, such as birth years or favorite sports teams. A general-knowledge or trivia question for which the answer can be accessed using a data base, such as country capitals or popular entertainers. Other data associated with the CAPTCHA may provide hints about its contents, such as an image whose filename contains the word that is used in the CAPTCHA.

What are the security consequences of Guessable CAPTCHA?+

If exploited, CWE-804 (Guessable CAPTCHA) it can compromise Access Control and Other, leading to outcomes such as Bypass Protection Mechanism and Other.

Which programming languages are affected by Guessable CAPTCHA?+

CWE-804 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 Guessable CAPTCHA?+

MITRE documents real CVEs mapped to CWE-804, including CVE-2022-4036. 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-804 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-804: Guessable CAPTCHA

Extended Description

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Detection Methods

Code Examples & CVEs

Observed CVE Examples (1)

CWE Relationships

Parent Weaknesses