What is the CVSS score of CVE-2026-21640?

CVE-2026-21640 has a CVSS 3.1 base score of 2.7 (Low). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-21640?

During next maintenance window: Apply vendor patches when convenient. Monitor vendor channels for updates.

Revive Adserver CVE-2026-21640

LOW

Use of Externally-Controlled Format String (CWE-134)

2026-01-20 support@hackerone.com

PHP Revive Adserver Aquaplatform

2.7

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-134 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V14 - Configuration Dependency management, component inventory
Impact	CVSS 2.7 (LOW). Attack vector: Network. Complexity: Low. Privileges required: High. User interaction: None. Exploitation requires authentication.
Exploit ScenarioDerived	An attacker (requires authentication) could exploit this vulnerability to compromise the affected system.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

HackerOne community member Faraz Ahmed (PakCyberbot) has reported a format string injection in the Revive Adserver settings. When specific character combinations are used in a setting, the admin user console could be disabled due to a fatal PHP error. [CVSS 2.7 LOW]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

Classified as CWE-134 (Use of Externally-Controlled Format String). Affects Revive Adserver. HackerOne community member Faraz Ahmed (PakCyberbot) has reported a format string injection in the Revive Adserver settings. When specific character combinations are used in a setting, the admin user console could be disabled due to a fatal PHP error.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 2.7 LOW

AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

DescriptionCVE.org

Executive ViewAI

Why It Matters

CVE-2026-21640 is a low-severity vulnerability (CVSS 2.7). The limited severity suggests constrained impact, typically requiring specific conditions or local access for exploitation. Apply vendor updates when available as part of routine maintenance.

Business Impact: Low

Compensating Controls

Apply vendor patch during routine maintenance. Standard security controls provide adequate interim protection.

Threat Intelligence Overview

EPSS Score

0.0%

Top 91% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

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 LOW

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

LOW severity (CVSS 0.1-3.9)

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

Defer

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact

Low

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +14

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Affected Products (CPE)CVE.org

cpe:2.3:a:aquaplatform:revive_adserver:*:*:*:*:*:*:*:*

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Same weakness CWE-134 – Use of Externally-Controlled Format String

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CVE-2012-10055 CRITICAL POC

9.3

CVE-2012-1851 CRITICAL

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CVE-2012-0809 HIGH POC

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CVE-2015-8617 CRITICAL POC

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References

Advisories & patches

REF https://hackerone.com/reports/3445332

Search Externally

GitHub PoC

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