Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
CWE-525 Variant Incomplete
Use of Web Browser Cache Containing Sensitive Information
This vulnerability occurs when a web application fails to implement secure caching directives, allowing sensitive user data or pages to be stored in the browser's cache where unauthorized parties…
Definition
What is CWE-525?
This vulnerability occurs when a web application fails to implement secure caching directives, allowing sensitive user data or pages to be stored in the browser's cache where unauthorized parties could retrieve them.
When a web server doesn't send the correct HTTP cache-control headers (like `no-store`, `private`, or appropriate `max-age`), browsers will save copies of pages, form data, or API responses by default. This means sensitive information such as login credentials, personal details, or session tokens could be written to the user's disk, remaining accessible after logout or even to other users on a shared computer.
To prevent this, developers must explicitly define a restrictive caching policy for all sensitive content. This involves setting HTTP response headers to instruct the browser not to cache certain pages or to cache them only privately. It's a critical security step that is often overlooked during development but is essential for protecting user privacy and data confidentiality.
Real-world impact
Real-world CVEs caused by CWE-525
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 pseudo
MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} 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-525
- Architecture and Design Protect information stored in cache.
- Architecture and Design / Implementation Use a restrictive caching policy for forms and web pages that potentially contain sensitive information.
- Architecture and Design Do not store unnecessarily sensitive information in the cache.
- Architecture and Design Consider using encryption in the cache.
Detection signals
How to detect CWE-525
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.
Plexicus auto-detects CWE-525 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-525?
How serious is CWE-525?
What languages or platforms are affected by CWE-525?
How can I prevent CWE-525?
How does Plexicus detect and fix CWE-525?
Where can I learn more about CWE-525?
Frequently asked questions
What is CWE-525?
This vulnerability occurs when a web application fails to implement secure caching directives, allowing sensitive user data or pages to be stored in the browser's cache where unauthorized parties could retrieve them.
How serious is CWE-525?
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-525?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-525?
Protect information stored in cache. Use a restrictive caching policy for forms and web pages that potentially contain sensitive information.
How does Plexicus detect and fix CWE-525?
Plexicus's SAST engine matches the data-flow signature for CWE-525 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-525?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/525.html. You can also reference OWASP and NIST documentation for adjacent guidance.
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