CVE-2026-89251: AVideo Authentication Bypass Vulnerability

CVE-2026-89251 Overview

CVE-2026-89251 is a missing origin validation vulnerability [CWE-345] in AVideo, an open-source video platform. The flaw exists in plugin/AD_Server/log.php through commit c3edcc274c389816d434acadac07ee78eaf330c1. The endpoint accepts ad impression events without verifying that an advertisement actually played. Any authenticated user can POST label=start requests repeatedly to credit the YPTWallet balance of arbitrary campaign video owners. This turns the ad accounting system into an open faucet for wallet inflation.

Critical Impact
Authenticated attackers can mint arbitrary YPTWallet credit for any campaign video owner by replaying fabricated ad-impression events, undermining the integrity of the platform's monetization ledger.

Affected Products

AVideo platform (WWBN/AVideo)
plugin/AD_Server/log.php component
All builds through commit c3edcc274c389816d434acadac07ee78eaf330c1

Discovery Timeline

2026-09-11 - CVE-2026-89251 published to the National Vulnerability Database
2026-09-11 - Last updated in NVD database

Technical Details for CVE-2026-89251

Vulnerability Analysis

AVideo ships an ad-serving plugin that records impression telemetry through plugin/AD_Server/log.php. The endpoint is intended to receive lifecycle events, such as start, when a viewer's browser actually renders an advertisement. Those events feed the YPTWallet accounting system, which credits the campaign video owner for each verified impression.

The log handler trusts the client-supplied label parameter without validating that the event came from a legitimate ad playback. It does not correlate the request with a signed impression token, a server-side ad session, or any anti-replay identifier. Any authenticated user can therefore submit arbitrary label values that the server treats as authoritative impression proof.

The resulting integrity gap sits entirely on the server-side ledger. Exploitation does not disclose data or crash the service, but it corrupts financial state that the platform later uses to disburse funds.

Root Cause

The root cause is insufficient verification of data authenticity [CWE-345]. log.php credits YPTWallet balances based on unauthenticated event labels rather than on evidence that an ad impression occurred. There is no cryptographic binding between the impression event and a rendered creative.

Attack Vector

An attacker registers or uses an existing low-privilege account. They then issue repeated HTTP POST requests to the AD Server log endpoint with label=start and the target campaign or video identifier. Each request increments the YPTWallet balance of the campaign video owner without any real ad play, allowing rapid inflation of arbitrary account balances.

Refer to the GitHub Security Advisory GHSA-cwrf-q9jv-44px and the VulnCheck Advisory on AVideo for additional technical context.

Detection Methods for CVE-2026-89251

Indicators of Compromise

Repeated POST requests to /plugin/AD_Server/log.php containing label=start from a single authenticated session or IP address.
YPTWallet balances that grow without a corresponding increase in unique viewers, session duration, or ad-render telemetry.
Wallet credit events attributed to campaign videos whose front-end player never emitted matching ad-start events.

Detection Strategies

Baseline the ratio of ad start events to unique authenticated sessions and alert when it exceeds normal viewer behavior.
Correlate log.php writes with browser-side ad player events; treat server-side events with no matching client telemetry as suspicious.
Review database changes to YPTWallet tables for bursts of small credits tied to a narrow set of campaign video IDs.

Monitoring Recommendations

Enable verbose web server logging for the plugin/AD_Server/ path, capturing request bodies, source IP, and user identifier.
Forward AVideo access and application logs to a centralized analytics platform for rate-based and behavioral analysis.
Alert on any single account submitting more than a threshold of ad log events per minute.

How to Mitigate CVE-2026-89251

Immediate Actions Required

Restrict access to plugin/AD_Server/log.php at the reverse proxy or web application firewall until a patched version is deployed.
Audit YPTWallet balances and disable payouts for accounts whose recent credit history cannot be reconciled with real viewer telemetry.
Rotate or invalidate low-privilege API sessions that show anomalous ad-log activity.

Patch Information

At the time of publication, the vulnerability is present through commit c3edcc274c389816d434acadac07ee78eaf330c1. Track the GitHub Security Advisory GHSA-cwrf-q9jv-44px for the fix commit and upgrade AVideo to the first release that includes server-side validation of ad impression events.

Workarounds

Disable the AD_Server plugin if advertising monetization is not in use.
Add a WAF rule that blocks or rate-limits POST requests to /plugin/AD_Server/log.php with label=start.
Require an authenticated, server-issued impression token in front of the log endpoint using an application gateway.

bash

# Example NGINX rate-limit and block for the vulnerable endpoint
limit_req_zone $binary_remote_addr zone=adlog:10m rate=5r/m;

location = /plugin/AD_Server/log.php {
    limit_req zone=adlog burst=5 nodelay;
    # Optional hard block until patched:
    # return 403;
}