CVE-2026-25700: Apache Answer Auth Bypass Vulnerability

CVE-2026-25700 Overview

CVE-2026-25700 is an Improper Restriction of Security Token Assignment vulnerability in Apache Answer through version 2.0.0. The flaw stems from administrative tokens remaining valid after the associated administrator account is suspended, deleted, or deactivated. Attackers holding a previously issued token retain access to administrative APIs until the token expires naturally. The Apache Software Foundation tracks this issue under [CWE-1259] and recommends upgrading to version 2.0.1.

Critical Impact
A revoked or terminated administrator can continue invoking administrative APIs in Apache Answer, preserving full confidentiality, integrity, and availability impact on the affected instance until the stolen or retained token expires.

Affected Products

Apache Answer versions up to and including 2.0.0
Apache Answer self-hosted deployments using session or API token authentication
Any Apache Answer instance that has suspended, deleted, or deactivated administrator accounts without forcing token rotation

Discovery Timeline

2026-06-10 - CVE-2026-25700 published to NVD
2026-06-10 - Last updated in NVD database

Technical Details for CVE-2026-25700

Vulnerability Analysis

Apache Answer is an open-source question-and-answer platform written in Go. Administrative actions in Apache Answer are authenticated using bearer tokens tied to administrator accounts. The vulnerability lies in the lifecycle management of these tokens. When an administrator account is suspended, deleted, or deactivated, the platform updates the account state but does not invalidate previously issued tokens server-side.

As a result, a token issued before account termination continues to authorize administrative API calls. The window of exposure equals the remaining token lifetime, not the moment of account revocation. This breaks the implicit security assumption that disabling an administrator immediately removes administrative access. The issue is classified under [CWE-1259] (Improper Restriction of Security Token Assignment).

Root Cause

The root cause is missing server-side token revocation logic during account state changes. Token validation checks signature and expiry but does not cross-reference the current state of the associated account. An attacker who obtained an administrator token before revocation, or a former administrator whose account was disabled, can replay the token against administrative endpoints.

Attack Vector

Exploitation requires network access to the Apache Answer instance and possession of a valid administrative token. The attacker submits standard HTTP requests to administrative API endpoints, including the unexpired bearer token in the Authorization header. No user interaction is required, and the attack complexity is low. Because the privileges associated with the token remain administrative, the attacker can manage users, modify content, alter configuration, and access sensitive data.

No public proof-of-concept exploit code has been published. The Apache mailing list advisory describes the issue without releasing exploitation details. See the Apache Mailing List Thread for the original disclosure.

Detection Methods for CVE-2026-25700

Indicators of Compromise

Administrative API requests originating from accounts that are currently marked suspended, deleted, or deactivated in the Apache Answer database
Successful authentication events using bearer tokens whose associated user_id no longer maps to an active administrator
Configuration or user-management changes performed outside the activity windows of currently active administrators

Detection Strategies

Correlate Apache Answer access logs with the user account state table to identify API calls authenticated by tokens belonging to inactive accounts
Alert on any HTTP request to /answer/admin/api/* paths where the authenticated principal has a non-active status flag
Review token issuance and last-use timestamps for accounts that have been disabled to detect post-revocation activity

Monitoring Recommendations

Forward Apache Answer web server and application logs to a centralized analytics platform for retention and correlation against identity state changes
Track administrative endpoint usage per token identifier and flag tokens that continue to be used after the associated account is modified
Audit the administrator account inventory weekly and verify that no tokens remain associated with disabled accounts

How to Mitigate CVE-2026-25700

Immediate Actions Required

Upgrade Apache Answer to version 2.0.1 or later, which invalidates previously issued tokens on account state changes
Manually invalidate all existing administrative tokens after upgrade by rotating signing secrets or clearing the token store
Audit administrator accounts and confirm that any suspended, deleted, or deactivated administrators no longer have active sessions
Reset credentials for any administrator whose access was revoked while running an affected version

Patch Information

The Apache Answer project addressed CVE-2026-25700 in version 2.0.1. The fix ensures that token validation considers the live state of the associated account and rejects tokens belonging to accounts that have been suspended, deleted, or deactivated. Refer to the Apache Mailing List Thread for the official advisory and upgrade guidance.

Workarounds

Rotate the application's token signing secret to forcibly invalidate all outstanding bearer tokens, requiring re-authentication
Restrict network access to administrative API endpoints using a reverse proxy or web application firewall, allowing only trusted IP ranges
Shorten the administrative token lifetime in configuration to reduce the post-revocation exposure window until the upgrade is applied

bash

# Configuration example: upgrade Apache Answer and rotate secrets
# 1. Pull the fixed release
docker pull apache/answer:2.0.1

# 2. Stop the running instance
docker stop answer && docker rm answer

# 3. Rotate the token signing secret in your environment file
sed -i 's/^TOKEN_SECRET=.*/TOKEN_SECRET=$(openssl rand -hex 32)/' .env

# 4. Start the patched container
docker run -d --name answer --env-file .env -p 9080:80 apache/answer:2.0.1