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Revive Adserver EUVDEUVD-2026-39601

| CVE-2026-50739 MEDIUM
Improper Access Control (CWE-284)
2026-06-26 hackerone GHSA-v78r-pfp2-f4c7
4.3
CVSS 3.0 · Vendor: hackerone
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate as low-privileged user
  2. Delivery
    Access tracker-campaigns.php via HTTP
  3. Exploit
    Craft reverse-link request targeting foreign campaign ID
  4. Execution
    Bypass missing ownership check
  5. Persist
    Associate own trackers with another manager's campaigns
  6. Impact
    Corrupt cross-manager ownership records

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK

1 technique across 1 tactic: Defense Evasion

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires an authenticated low-privileged user account on the Revive Adserver instance (confirmed by CVSS PR:L). The instance must host multiple manager accounts with separate campaign ownership for cross-manager abuse to be meaningful - single-manager deployments have no exploitable trust boundary to cross. The specific vulnerable operation is the reverse linking action in tracker-campaigns.php (linking campaigns to trackers, as opposed to the forward direction fixed in CVE-2026-34913). Network access to the Revive Adserver web interface is required (CVSS AV:N). No user interaction by a victim is needed (CVSS UI:N), and no non-default configuration is required beyond the multi-manager deployment model.

Impact

The CVSS 3.0 score of 4.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N) accurately reflects the bounded impact of this flaw. Attack vector is network with low complexity, meaning no special positioning or chained preconditions are needed beyond holding a valid low-privileged account. Impact is strictly limited to low integrity, with no confidentiality or availability effect, consistent with the nature of the abuse: polluting campaign-tracker ownership records rather than accessing or destroying data. No EPSS score is available in the provided data, but the absence of KEV listing and no known public exploit code suggest limited real-world exploitation activity. The primary risk is to multi-tenant shared Revive Adserver deployments where isolation between manager accounts is a trust boundary. Single-manager instances are not exposed to meaningful harm from this issue. The risk is real but operationally narrow.

Exploit ScenarioDerived

An attacker holding a low-privileged account on a shared Revive Adserver instance sends a crafted HTTP request to tracker-campaigns.php specifying a campaign ID owned by a different manager. Because ownership validation is absent for this reverse linking path, the server accepts the request and creates a tracker-campaign association across manager boundaries. No public exploit code has been identified at time of analysis, but the low complexity and network accessibility make manual reproduction straightforward for any authenticated user.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 26, 2026

Ownership validation bypass in Revive Adserver 6.0.7 and earlier allows a low-privileged authenticated user to link their own trackers to campaigns belonging to other managers on the same instance via the tracker-campaigns.php script. This is a bypass of the fix introduced for CVE-2026-34913, which applied ownership checks only to the forward linking operation but omitted the reverse direction. The impact is confined to integrity - specifically, creation of inconsistent cross-manager ownership relationships - with no confidentiality or availability consequences. No public exploit identified at time of analysis.

RemediationAI

Upgrade Revive Adserver to a version that incorporates the corrected ownership validation for the reverse tracker-campaign linking operation in tracker-campaigns.php. No exact patched release version is confirmed from the available reference data; the HackerOne report at https://hackerone.com/reports/3780709 should be consulted for the vendor's official fix version once the report becomes public. As a compensating control for multi-manager deployments pending a patch, administrators can restrict low-privileged users' access to the tracker-campaigns.php endpoint via web server ACLs or application-level role restrictions, accepting the trade-off that tracker-campaign linking functionality will be unavailable to those users. Single-manager deployments face negligible risk and no immediate action is required beyond monitoring for an official patch.

Affected VersionsENISA

Adserver 0 ≤6.0.7

Affected Packages

euvd adserver no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Revive Adserver is an open-source PHP-based ad serving platform (cpe:2.3:a:revive:adserver:*:*:*:*:*:*:*:*). The tracker-campaigns.php script manages the bidirectional relationship between tracker and campaign entities. The prior fix for CVE-2026-34913 introduced ownership validation for one direction of this linking operation but failed to apply the same guard to the reverse operation, a classic incomplete-fix pattern. CWE-284 (Improper Access Control) captures the root cause: the authorization decision - verifying campaign ownership before permitting a link - was not uniformly enforced across all code paths executing the same logical action. The PHP tag confirms the server-side language context and that no client-side exploitation is involved.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (hackerone) PRIMARY 4.3 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
vuln.today AI 4.3 MEDIUM

Low-privilege authentication required over network; impact is integrity-only, limited to cross-manager ownership record pollution with no confidentiality or availability effect.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (hackerone).

CVSS VectorVendor: hackerone

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

DescriptionCVE.org

A bypass for CVE‑2026‑34913 exists with proper ownership validation that had not been applied to the reverse operation of linking campaigns and trackers through the tracker-campaigns.php script in Revive Adserver 6.0.7 and earlier. As a result, a low‑privileged user could link their trackers to campaigns owned by other managers on the same instance, leading to inconsistent ownership relationships.

Threat Intelligence Overview

EPSS Score
0.2%
Top 93% exploitable
Prevalence
Low
niche open-source ad server with limited enterprise footprint
Social Media
1
Sightings
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +22
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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