CVE-2026-25699: Apache Answer Authorization Bypass Exposes Private Content

Technical summary

The vulnerability stems from insufficient authorization validation in Apache Answer's timeline APIs. While the APIs require authentication (ruling out anonymous access), they fail to enforce proper permission checks before returning sensitive data. This allows an authenticated attacker to enumerate and retrieve deleted, private, or unpublished content and track all historical changes to that content. The issue affects Apache Answer through version 2.0.0 and is classified under CWE-359 (Exposure of Private Personal Information to an Unauthorized Actor).

Business impact

Organizations deploying Apache Answer face a confidentiality breach risk. Users' private submissions, deleted content, and internal revision histories become visible to any employee or contractor with basic system access. This exposure could compromise sensitive information sharing, internal deliberations, or draft content that was never intended for publication. While integrity and availability remain unaffected, the information disclosure could damage trust and create compliance liabilities depending on the nature of exposed data and applicable regulations.

Affected systems

The vulnerability affects Apache Answer versions 2.0.0 and earlier. Organizations running any version at or below 2.0.0 should be considered at risk. Version 2.0.1 and later contain the necessary authorization fixes. No other Apache products or third-party integrations are mentioned as affected by this specific flaw.

Exploitability

Exploitation requires valid user credentials—an attacker cannot exploit this vulnerability anonymously. However, the barrier to entry is low: any authenticated user account (including low-privilege accounts) can trigger the unauthorized data access. The vulnerability requires user interaction (UI:R in the CVSS vector), likely meaning the attacker must craft API calls or use browser developer tools to access the timeline endpoints directly. The attack surface is network-accessible, and no special configuration or race conditions are needed, making it relatively straightforward to exploit once an attacker has valid credentials.

Remediation

Upgrade Apache Answer to version 2.0.1 or later immediately. The patch restores proper authorization checks to timeline-related APIs, ensuring that authenticated users can only access content they have explicit permission to view. Organizations unable to upgrade immediately should review access controls and audit logs to detect unauthorized data access. Consider restricting API access to trusted networks or implementing additional authentication layers until patching is complete.

Patch guidance

Apache Answer users should prioritize upgrading to version 2.0.1. Consult the official Apache Answer release notes and vendor advisory for any breaking changes or migration steps. Before deploying to production, test the upgrade in a staging environment to verify that legitimate timeline operations continue to function correctly and that no dependent integrations are disrupted. If immediate patching is not possible, document the risk and establish a remediation timeline.

Detection guidance

Monitor Apache Answer's timeline API endpoints for unusual access patterns, particularly requests from low-privilege accounts accessing content marked as private, deleted, or unapproved. Review API logs for calls to `/api/timeline/*` or similar endpoints from users who shouldn't have permission to that data. Audit the revision history API for systematic enumeration attempts. Check access logs for authenticated sessions making repeated requests to different content IDs in a short timeframe—a potential sign of automated exploitation. Implement alerting on failed authorization checks if your deployment includes detailed logging.

Why prioritize this

This vulnerability merits prompt attention due to its combination of easy exploitation (any authenticated user can trigger it), direct information disclosure impact, and potential for sensitive data exposure. The CVSS 6.1 MEDIUM score reflects the confidentiality breach risk, while the lack of authentication barriers and network accessibility increase practical urgency. Organizations where Apache Answer hosts sensitive discussions, drafts, or internal deliberations should prioritize this higher than the base score suggests.

Risk score, explained

The CVSS 3.1 score of 6.1 MEDIUM (AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N) reflects a network-accessible vulnerability with low attack complexity, no special privileges required, and user interaction needed. It assigns partial impact to confidentiality and integrity, with no availability impact. The score is reasonable given that exploitation requires valid credentials and user interaction, but security teams should weight their own risk higher if Apache Answer hosts highly sensitive content or if your environment grants broad user access to the platform.

Frequently asked questions