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Monica CVE-2026-26747

CRITICAL
Improper Neutralization of HTTP Headers for Scripting Syntax (CWE-644)
2026-02-20 cve@mitre.org
PHP Monica Monicahq
9.1
CVSS 3.1 · NVD
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Attack ChainAIDerived

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

  1. Access
    Send password reset request
  2. Delivery
    Craft malicious Host header
  3. Exploit
    Application generates poisoned reset link
  4. Execution
    Attacker receives password reset token
  5. Impact
    Compromise target account

Vulnerability Assessment

Weakness
CWE
CWE-644
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization HTTP header neutralization
Exploitation Conditions

Monica 4.1.2 with 'app.force_url' configuration set to false (default). Attacker exploits improper Host header handling in AppServiceProvider.php to inject malicious domain into password reset emails. No authentication required.
Impact

CVSS 9.1.
Exploit ScenarioDerived

Poison password reset links via Host header.
Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Host Header Poisoning in Monica 4.1.2 CRM. PoC available.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 22:04 CVSS 9.1

Host header poisoning in Monica CRM.

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Technical ContextAI · show details

CWE-644 improper Host header handling.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

NVD PRIMARY 9.1 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

Lifecycle Timeline

2
PoC Detected
Feb 26, 2026 - 02:42 vuln.today
Public exploit code
CVE Published
Feb 20, 2026 - 17:25 nvd
CRITICAL 9.1

DescriptionCVE.org

A Host Header Poisoning vulnerability exists in Monica 4.1.2 due to improper handling of the HTTP Host header in app/Providers/AppServiceProvider.php, combined with the default misconfiguration where the "app.force_url" is not set and default is "false". The application generates absolute URLs (such as those used in password reset emails) using the user-supplied Host header. This allows remote attackers to poison the password reset link sent to a victim,

Executive ViewAI

Why It Matters

A critical vulnerability in Monica versions up to 4.1.2 allows attackers to intercept and manipulate password reset links, potentially compromising user accounts organization-wide. With a public exploit available and no patch released, immediate action is required to prevent unauthorized account takeovers and data breaches.

Business Impact: Severe
Compensating Controls

Disable password reset feature until patch available; implement WAF rules to detect anomalous reset link patterns; segment Monica instances behind VPN/bastion hosts; enforce multi-factor authentication on all Monica accounts; monitor email logs for suspicious password reset communications; implement DMARC/SPF/DKIM to prevent email spoofing; require out-of-band password reset verification (phone/security questions).

Threat Intelligence Overview

EPSS Score
0.1%
Top 84% exploitable
Exploit
POC
Public exploit code exists
Data Quality
4 sources
Confidence: Medium
NVD CVE.org EPSS GitHub

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 CRITICAL
CISA KEV No
Public POC Yes
EPSS 0.1%
Patch available No
Active threat No
Deciding rule
CRITICAL severity + public POC available
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
Out-of-Cycle
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
Very High

Priority Score

66
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +46
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Affected Products (CPE)CVE.org

cpe:2.3:a:monicahq:monica:4.1.2:*:*:*:*:*:*:*

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Same weakness CWE-644 – Improper Neutralization of HTTP Headers for Scripting Syntax

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References

Advisories & patches
REF https://github.com/monicahq/monica

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