CWE-488: Exposure of Data Element to Wrong Session

The product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session.

Data can "bleed" from one session to another through member variables of singleton objects, such as Servlets, and objects from a shared pool. In the case of Servlets, developers sometimes do not understand that, unless a Servlet implements the SingleThreadModel interface, the Servlet is a singleton; there is only one instance of the Servlet, and that single instance is used and re-used to handle multiple requests that are processed simultaneously by different threads. A common result is that developers use Servlet member fields in such a way that one user may inadvertently see another user's data. In other words, storing user data in Servlet member fields introduces a data access race condition.

Consequences

• Confidentiality: Read Application Data

How to prevent it

• Architecture and Design: Protect the application's sessions from information leakage. Make sure that a session's data is not used or visible by other sessions.
• Testing: Use a static analysis tool to scan the code for information leakage vulnerabilities (e.g. Singleton Member Field).
• Architecture and Design: In a multithreading environment, storing user data in Servlet member fields introduces a data access race condition. Do not use member fields to store information in the Servlet.

Recent advisories

• GHSA-c476-6w5q-jw77 — rclone: FTP cross-session auth-proxy backend confusion
• EEF-CVE-2026-82367 — Re-entrant synchronous publish in AshGraphql subscription batcher delivers one subscriber's records to another's topic
• GHSA-f23p-vx2j-j53r — Hono: `memo()` retains SSR output across requests, leading to cross-user data disclosure
• GHSA-9h85-g7w3-rh49 — ViewComponent: Reused Component Instances Retain Stale Render Context
• GHSA-9c38-2mcm-q7f7 — n8n: Merge Node SQL Mode Prototype Pollution
• GHSA-mfvp-7p3v-x9mh — Casdoor SAML callback handler accepts any well-formed SAMLResponse sent to /api/acs without verifying that it corresponds to an AuthnRequest
• GHSA-fcjp-h8cc-6879 — NATS is vulnerable to MQTT hijacking via Client ID
• GHSA-7w6r-748w-mh52 — pgAdmin has Incorrect Default Permissions
• GHSA-9442-gm4v-r222 — Undertow's url-encoded request path information can be broken on ajp-listener
• GHSA-82vp-jr39-4j2j — TYPO3 Security Misconfiguration in Frontend Session Handling
• GHSA-wrqv-pf6j-mqjp — Deno's Node.js Compatibility Runtime has Cross-Session Data Contamination
• GHSA-97g8-xfvw-q4hg — Keycloak vulnerable to session takeover with OIDC offline refreshtokens

All advisories for CWE-488