CVE-2026-50739: Revive Adserver Auth Bypass Vulnerability

CVE-2026-50739 Overview

CVE-2026-50739 is a broken access control vulnerability in Revive Adserver 6.0.7 and earlier. The flaw exists in the tracker-campaigns.php script, which handles the linking of trackers to campaigns. It represents a bypass of the prior fix for CVE-2026-34913, where ownership validation was not applied to the reverse linking operation. A low-privileged user can link their own trackers to campaigns owned by other managers on the same instance. The result is inconsistent ownership relationships across the ad server, allowing cross-tenant data associations that violate the intended authorization model [CWE-284].

Critical Impact
Authenticated low-privileged users can associate their trackers with campaigns owned by other managers, breaking multi-tenant ownership boundaries in Revive Adserver.

Affected Products

Revive Adserver 6.0.7 and earlier
Component: tracker-campaigns.php script
Deployments: multi-manager instances of Revive Adserver

Discovery Timeline

2026-06-26 - CVE-2026-50739 published to NVD
2026-06-29 - Last updated in NVD database

Technical Details for CVE-2026-50739

Vulnerability Analysis

The vulnerability resides in the tracker-to-campaign linking workflow of Revive Adserver. A prior issue tracked as CVE-2026-34913 was patched by adding ownership validation on one direction of the linking operation. The fix did not cover the reverse operation exposed via tracker-campaigns.php. As a result, the script accepts requests to associate a user-owned tracker with a campaign object that belongs to a different manager account. The server-side handler validates the requester's ownership of the tracker but fails to verify ownership of the target campaign. This inconsistency allows manipulation of cross-owner relationships within a shared instance and undermines the manager-based isolation model.

Root Cause

The root cause is incomplete access control enforcement (CWE-284). Authorization checks were applied to the forward linking flow but omitted from the reverse flow exposed through tracker-campaigns.php. The handler trusts the campaign identifier supplied in the request without confirming that the authenticated user owns or has delegated rights over that campaign. This gap allows a low-privileged manager to establish links to resources outside their authorization scope.

Attack Vector

The attack is network-based and requires an authenticated account with low privileges on a shared Revive Adserver instance. An attacker with a valid manager session sends a linking request through tracker-campaigns.php referencing a campaign identifier belonging to a different manager. The server processes the association without ownership verification, producing an unauthorized tracker-to-campaign link. No user interaction is required from the victim manager. See the HackerOne Report #3780709 for reference details.

No verified public exploit code is available for CVE-2026-50739. The vulnerability mechanism is described in prose because no sanitized proof-of-concept has been published in an authoritative source.

Detection Methods for CVE-2026-50739

Indicators of Compromise

Unexpected entries in the tracker-campaign association tables linking objects owned by different manager accounts.
Web server access logs showing POST or GET requests to tracker-campaigns.php referencing campaign identifiers outside the authenticated user's owned set.
Audit log entries where the actor manager ID does not match the owner of the referenced campaign or tracker.

Detection Strategies

Run periodic database consistency queries that join trackers and campaigns on their owning manager IDs and flag mismatches.
Correlate application audit logs with session identity to detect linking actions performed against resources outside the actor's ownership scope.
Alert on repeated tracker-campaigns.php requests referencing campaign IDs the requester does not own.

Monitoring Recommendations

Enable verbose application logging for tracker and campaign management endpoints in Revive Adserver.
Forward web server and application logs to a centralized log platform and build queries for cross-owner linking events.
Baseline normal manager activity and alert on deviations such as sudden linking activity spanning multiple owners.

How to Mitigate CVE-2026-50739

Immediate Actions Required

Upgrade Revive Adserver to a release later than 6.0.7 that contains the fix for CVE-2026-50739.
Audit existing tracker-to-campaign links for cross-owner associations and remove or reassign unauthorized links.
Review manager account inventory and disable inactive or untrusted low-privileged accounts.

Patch Information

Revive Adserver 6.0.7 and earlier are affected. Administrators should apply the vendor-supplied update that adds ownership validation to the reverse linking operation in tracker-campaigns.php. Refer to the HackerOne Report #3780709 for the disclosure record and vendor coordination details.

Workarounds

Restrict access to the Revive Adserver management interface to trusted networks using firewall or reverse proxy rules until the patch is applied.
Limit the creation of new manager accounts and review permissions granted to existing low-privileged users.
Deploy web application firewall rules that inspect requests to tracker-campaigns.php and block linking actions where the target campaign owner differs from the authenticated user.

bash

# Example WAF-style rule concept to block cross-owner linking requests
# (adapt to your WAF syntax; pseudocode only)
SecRule REQUEST_URI "@endsWith /tracker-campaigns.php" \
  "phase:2,deny,status:403,id:1050739,\
   msg:'Block suspicious cross-owner linking in Revive Adserver',\
   chain"
  SecRule ARGS:campaignid "@rx ^[0-9]+$" \
    "chain"
    SecRule &SESSION:owned_campaign_ids "@eq 0"