CVE-2025-56527: Kotaemon Information Disclosure Flaw

CVE-2025-56527 Overview

CVE-2025-56527 is an information disclosure vulnerability in Cinnamon Kotaemon 0.11.0, an open-source retrieval-augmented generation (RAG) application. The application stores user credentials in plaintext within the browser's localStorage, exposing passwords to any process or script that can read client-side storage. An attacker who gains access to the browser context, through stored cross-site scripting (XSS), malicious extensions, or local access, can retrieve credentials without further authentication. The issue is tracked under CWE-256: Plaintext Storage of a Password.

Critical Impact
Plaintext credentials stored in localStorage are persistently accessible to client-side scripts, enabling account takeover when combined with XSS or local browser access.

Affected Products

Cinnamon Kotaemon version 0.11.0
Kotaemon client-side authentication module
Browser sessions persisting localStorage data for affected deployments

Discovery Timeline

2025-11-18 - CVE-2025-56527 published to the National Vulnerability Database
2025-12-02 - Last updated in NVD database

Technical Details for CVE-2025-56527

Vulnerability Analysis

Kotaemon 0.11.0 persists authentication credentials in the browser's localStorage using plaintext encoding. localStorage is a synchronous, origin-scoped key-value store that any JavaScript executing in the same origin can read. Storing passwords in this location violates secure credential handling practices because the data is not encrypted, never expires automatically, and survives browser restarts.

The storage location makes credentials available to any script with same-origin access. This includes injected scripts via stored XSS, browser extensions with broad host permissions, and offline forensic recovery from the browser profile. The same vendor disclosure links this issue to a parallel stored XSS vulnerability (CVE-2025-56526) in PDF content rendering, which directly amplifies the impact by giving attackers a path to execute scripts within the application origin.

Root Cause

The root cause is an insecure client-side credential persistence design. Authentication tokens or passwords that must survive page reloads should be held in HttpOnly, Secure, SameSite cookies or in server-side session stores. The Kotaemon client instead writes raw credential material directly into localStorage, where no browser-level isolation prevents script access.

Attack Vector

An attacker exploits the vulnerability by executing JavaScript in the Kotaemon origin and reading the credential keys from localStorage. The most direct chain combines this issue with CVE-2025-56526, where unsanitized PDF content rendering yields stored XSS. Once script execution is achieved, the attacker exfiltrates credentials to an external endpoint. Local attackers with file system access to the browser profile can also extract the stored values offline.

No verified proof-of-concept code is published for CVE-2025-56527 itself. Technical details are available in the GitHub CVE Disclosure and the Notion Security Analysis.

Detection Methods for CVE-2025-56527

Indicators of Compromise

Presence of plaintext password values under the Kotaemon origin in browser localStorage
Outbound HTTP requests from the Kotaemon application origin to unknown domains carrying credential-shaped payloads
Stored documents (PDFs) containing embedded <script> tags or JavaScript URI handlers
Authentication events from new IP addresses or user agents reusing valid credentials

Detection Strategies

Inspect deployed Kotaemon 0.11.0 instances and confirm whether credential keys are written to localStorage after login
Review web server access logs for unusual fetch or XHR requests originating from authenticated sessions to non-application domains
Hunt for stored XSS payloads in uploaded documents, since CVE-2025-56526 is the primary exploitation path for this issue

Monitoring Recommendations

Enable authentication anomaly monitoring for password reuse across geographies and devices
Forward Kotaemon application and reverse proxy logs to a centralized analytics platform for correlation
Alert on Content Security Policy (CSP) violations that indicate script injection attempts in the Kotaemon origin

How to Mitigate CVE-2025-56527

Immediate Actions Required

Upgrade Kotaemon beyond 0.11.0 to a build that includes commit 37cdc28 from the upstream repository
Force a password reset for every user who authenticated to an affected instance
Instruct users to clear localStorage for the Kotaemon origin after upgrading
Rotate any API keys, OAuth tokens, or third-party secrets configured in the application

Patch Information

The vendor has published a fix referenced in the GitHub Commit 37cdc28. Operators should deploy the patched build, verify that credentials are no longer written to localStorage, and confirm that authentication state is held in secure HTTP-only cookies or server-side sessions. Additional context is available in the Kotaemon project repository.

Workarounds

Restrict Kotaemon access to trusted internal networks behind a VPN or zero-trust proxy until patched
Disable PDF upload and rendering to reduce exposure to the chained stored XSS vector (CVE-2025-56526)
Deploy a strict Content Security Policy that blocks inline scripts and unknown script sources for the Kotaemon origin
Configure short-lived authentication sessions and enforce multi-factor authentication on identity providers fronting the application

bash

# Example strict CSP header for the Kotaemon reverse proxy
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; frame-ancestors 'none'; base-uri 'self';" always;