42/100 CVSS 7.4 🔴 CVE ANALYSISPublished: May 11, 2026

Yii 2: Local file inclusion via view parameter name collision

The core view rendering method `View::renderPhpFile()` calls `extract($_params_, EXTR_OVERWRITE)` before the `require` statement that includes the view file. A caller-controlled parameter named `_file_` in the `$params` array overwrites the internal local variable that specifies which file is included — enabling a Local File Inclusion primitive. ##...

7.4

CVSS Score

LOW

Threat Level

Priority /100

TBD

Exploited ITW

Monitor

CISA Status

Sources

🔵

HIGH-PRIORITY SECURITY ADVISORY — Priority Score: 42/100

CVSS 7.4 LOW. SENTINEL APEX recommends immediate patch evaluation. Intelligence from 1 confirmed source(s).

📋 Executive Summary

⚡ Analyst Assessment — SENTINEL APEX v4.0

This report analyzes CVE-2026-39850 affecting composer yiisoft/yii2. Composite threat score: 42/100. Intelligence corroborated across 1 source(s): github_advisories. CVSS base score: 7.4. No confirmed in-the-wild exploitation at the time of writing; prioritize on exposure, privilege, and CVSS.

Intelligence sources: github_advisories

⚠️ Business Impact Analysis

⚠️ Remote code execution — full server takeover without authentication possible

🔗 Representative Attack Path

A typical attack path for this vulnerability class, mapped to MITRE ATT&CK — a representative model to guide detection and defense, not a claim of observed activity against a specific target. Confirm specifics against the primary sources below.

#	Phase	Attacker Action	MITRE
1	Reconnaissance	Attacker identifies exposed yiisoft/yii2 instances via Shodan, Censys, or targeted scanning	`TA0043`
2	Initial Access	Exploitation of CVE-2026-39850 in composer yiisoft/yii2	`T1190`
3	Execution	Remote code execution achieved — attacker runs arbitrary commands on target system	`T1203`
4	Persistence	Backdoor, scheduled task, or new admin account created for persistent access	`T1053`
5	Command & Control	Attacker establishes persistent C2 channel using HTTPS or DNS tunneling	`T1071`
6	Impact / Objectives	Intellectual property theft, espionage, cryptomining, or preparation for future attack stage	`T1657`

⚠ Deep Dive Analysis

This high-severity vulnerability in composer yiisoft/yii2 (CVSS 7.4) represents a significant attack surface. SENTINEL APEX assesses exploitation to be technically feasible with moderate effort. Organizations running yiisoft/yii2 in internet-facing or privileged positions face immediate risk.

SENTINEL APEX URGENCY: ELEVATED. Score: 42/100 LOW. Patch before exploitation activity begins.

🎯 MITRE ATT&CK Mapping

Category	Mapping
Primary Tactic	Execution
Primary Technique	T1203 — Exploitation for Client Execution
Sub-Technique	T1059 — Command & Scripting Interpreter
Weakness (CWE)	CWE-20
Intel Type	🔴 CVE ANALYSIS
Source(s)	github_advisories

🔴 CVE Reference

CVE ID	Reference	Score
CVE-2026-39850	NVD →	7.4
CVE-2026-39850	NVD →	7.4

🔍 Detection Rules — Sigma (SIEM)

Deploy to Splunk, Elastic, Microsoft Sentinel, or QRadar. SOC Pro subscribers receive pre-compiled SIEM-native query packs updated with each pipeline run.

Sigma YAMLtitle: CVE-2026-39850 Exploitation Attempt — composer yiisoft/yii2
id: 8c0e68d16072a249-71bc
status: experimental
description: Detects exploitation of CVE-2026-39850 in composer yiisoft/yii2. Priority: LOW. Score: 42/100
author: CYBERDUDEBIVASH SENTINEL APEX v4.0 (bivash@cyberdudebivash.com)
date: 2026-05-11
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-39850
    - https://blog.cyberdudebivash.in/
tags:
    - attack.initial_access
    - attack.t1190
    - cve-2026-39850
    - cve-2026-39850
logsource:
    category: webserver
detection:
    keywords:
        - 'CVE-2026-39850'
        - 'CVE-2026-39850'
        - 'cve-2026-39850'
    condition: keywords
falsepositives:
    - Security scanners
level: medium

📡 Detection Rules — YARA (Endpoint)

Deploy to endpoint detection platforms. Enterprise subscribers receive tuned, FP-validated YARA rule packs.

YARArule CVE_2026_39850_Exploitation {
    meta:
        description = "Detects artifacts related to CVE-2026-39850 exploitation in composer yiisoft/yii2"
        author      = "CYBERDUDEBIVASH SENTINEL APEX v4.0"
        date        = "2026-05-11"
        severity    = "HIGH"
        cvss        = "7.4"
        priority    = "42/100"
        threat_level = "LOW"
        reference   = "https://nvd.nist.gov/vuln/detail/CVE-2026-39850"
    strings:
        $id_str  = "CVE-2026-39850" ascii nocase
        $product = "yiisoft_yii2" ascii nocase wide
    condition:
        any of them
}

🛡️ SOC Response Playbook

1IMMEDIATE (0-1hr): Identify all instances of yiisoft/yii2 in your environment via CMDB/asset inventory
2IMMEDIATE (0-1hr): Apply vendor patch — no maintenance window exception for LOW threats
3IMMEDIATE (1-2hr): If no patch available: implement WAF rules, ACLs, or network-level compensating controls
4SHORT-TERM (2-4hr): Deploy Sigma detection rule to SIEM — validate alert generation in test environment
5SHORT-TERM (4-8hr): Review logs for exploitation indicators (anomalous yiisoft/yii2 requests, error spikes)
6SHORT-TERM (8-24hr): Hunt for post-exploitation: new admin accounts, scheduled tasks, lateral movement
7MONITOR: Subscribe to composer security advisories for patch updates
8ONGOING: Track SENTINEL APEX intelligence feed for follow-on campaigns targeting yiisoft/yii2

📎 Intelligence References

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⚡ CYBERDUDEBIVASH SENTINEL APEX v4.0

Intelligence report generated by CYBERDUDEBIVASH SENTINEL APEX v4.0
Report ID: SENTINEL-CVE-2026-39850-2026-05-11 | Priority: 42/100 LOW | Sources: 1
© 2026 CYBERDUDEBIVASH PRIVATE LIMITED
Republication requires written attribution to CYBERDUDEBIVASH SENTINEL APEX

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