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.)
CWE-539 Variant Incomplete
Use of Persistent Cookies Containing Sensitive Information
This vulnerability occurs when a web application stores sensitive data, like authentication details or personal information, within persistent cookies that remain on a user's device.
Definition
What is CWE-539?
This vulnerability occurs when a web application stores sensitive data, like authentication details or personal information, within persistent cookies that remain on a user's device.
Cookies are small pieces of data set by a web application and stored locally in a user's browser. While they are essential for maintaining state—like keeping a user logged in or remembering site preferences—they become a security risk when sensitive information is written directly into a cookie that is saved to disk. Unlike session cookies, which are deleted when the browser closes, persistent cookies remain on the hard drive for a defined period, making the sensitive data they contain accessible long-term.
Storing sensitive data such as usernames, passwords, session tokens, or personal details in a persistent cookie exposes it to theft or misuse. Attackers can extract these cookies from browser files or through cross-site scripting (XSS) attacks, potentially leading to account takeover or privacy violations. Developers should instead use persistent cookies only for non-sensitive identifiers, storing the actual sensitive data securely on the server side where it can be properly protected.
Real-world impact
Real-world CVEs caused by CWE-539
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-539
- Architecture and Design Do not store sensitive information in persistent cookies.
Detection signals
How to detect CWE-539
CWE-539
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Frequently asked questions What is CWE-539?
How serious is CWE-539?
What languages or platforms are affected by CWE-539?
How can I prevent CWE-539?
How does Plexicus detect and fix CWE-539?
Where can I learn more about CWE-539?
Frequently asked questions
What is CWE-539?
This vulnerability occurs when a web application stores sensitive data, like authentication details or personal information, within persistent cookies that remain on a user's device.
How serious is CWE-539?
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-539?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-539?
Do not store sensitive information in persistent cookies.
How does Plexicus detect and fix CWE-539?
Plexicus's SAST engine matches the data-flow signature for CWE-539 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-539?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/539.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-539
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CWE-529 Sibling
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CWE-530 Sibling
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CWE-553 Sibling
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