CVE-2025-29868: Apache Answer Information Disclosure Flaw

CVE-2025-29868 Overview

CVE-2025-29868 is an information disclosure vulnerability in Apache Answer, an open-source Q&A platform maintained by the Apache Software Foundation. The flaw affects all versions through 1.4.2 and stems from unrestricted rendering of externally referenced images. When a user views content containing an external image, the user's browser retrieves that image directly from the third-party host, exposing the user's IP address to the image provider. The vulnerability is classified under CWE-495: Private Data Structure Returned From A Public Method. Apache resolved the issue in version 1.4.5 by allowing administrators to control whether external content is displayed.

Critical Impact
Attackers hosting externally referenced images can harvest IP addresses and request metadata from any Apache Answer user who views the affected content, enabling reconnaissance and user tracking.

Affected Products

Apache Answer versions through 1.4.2
Deployments allowing external image references in user-generated content
Self-hosted Apache Answer instances exposed to untrusted contributors

Discovery Timeline

2025-04-01 - CVE-2025-29868 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-29868

Vulnerability Analysis

Apache Answer renders user-submitted content that may include images referenced by external URLs. When another user views the post, the browser issues an HTTP request to the external host to retrieve the image. This request carries client metadata including the source IP address, User-Agent, and Referer header. The image provider consequently learns which users viewed which content, along with approximate geographic location derived from the IP address.

The issue is categorized as [CWE-495], where a public method exposes internal or private data. In this case, the private data is the client's network identity, which the platform indirectly leaks by proxying image rendering to arbitrary third-party hosts. The vulnerability requires no authentication for exploitation and no user interaction beyond viewing affected content.

Root Cause

Apache Answer through 1.4.2 did not provide administrators with a control to restrict or proxy externally referenced media. Any authenticated contributor could embed remote image URLs into posts, comments, or profile fields. The client-side rendering forced viewers to make direct requests to attacker-controlled hosts.

Attack Vector

An attacker with posting privileges embeds an image URL pointing to a server they control. Every user who subsequently views the post triggers a request to the attacker's server. The attacker collects request logs containing viewer IP addresses, timestamps, and browser fingerprints. This can be combined with account correlation to deanonymize specific users on the platform.

The vulnerability manifests in the content rendering pipeline. See the Apache Security Mailing List Thread for the vendor advisory.

Detection Methods for CVE-2025-29868

Indicators of Compromise

Posts, comments, or profile content containing <img> tags or Markdown image references pointing to unfamiliar external domains
Outbound HTTP requests from user browsers to non-CDN third-party image hosts when viewing Apache Answer content
Unusual patterns of newly registered accounts posting content containing external image references

Detection Strategies

Audit the Apache Answer database for stored content containing external URLs in image fields, especially domains not on an approved list
Review web proxy or DNS logs for outbound requests generated by users interacting with the Answer platform
Correlate account activity with content submissions that include remote image references from low-reputation domains

Monitoring Recommendations

Log and inspect all outbound HTTP requests originating from Apache Answer client sessions
Monitor Apache Answer version banners across the environment to identify instances still running 1.4.2 or earlier
Track administrative configuration changes to the external content display setting introduced in 1.4.5

How to Mitigate CVE-2025-29868

Immediate Actions Required

Upgrade Apache Answer to version 1.4.5 or later, which introduces administrative control over external content display
Disable external content rendering in the administrative settings once upgraded
Audit existing user-generated content for external image references and remove or replace them with locally hosted assets

Patch Information

Apache released version 1.4.5 to remediate CVE-2025-29868. The fixed release adds an administrator-controlled setting that determines whether external content can be displayed. Refer to the Apache Security Mailing List Thread and the OpenWall OSS Security notification for release details.

Workarounds

Deploy a reverse proxy or content rewriting layer that proxies external images through a server-side fetcher, preventing direct client-to-attacker requests
Restrict posting privileges to trusted users until the upgrade is completed
Apply a Content Security Policy (CSP) img-src directive limiting image loads to approved domains

bash

# Example CSP header restricting image sources to the Answer instance and a trusted CDN
add_header Content-Security-Policy "img-src 'self' https://cdn.example.com; default-src 'self'";