43/100 CVSS 7.5 🔴 CVE ANALYSISPublished: July 6, 2026

Craft CMS: DOM XSS via GitHub issue title in CraftSupport widget

## Summary An attacker with only a GitHub account can plant a JavaScript payload in a `craftcms/cms` issue title. When a Craft admin uses the CraftSupport widget’s "Give feedback" screen and types a search term that returns the poisoned issue, the payload executes in the admin’s control panel session. No control panel account or elevated privileges...

7.5

CVSS Score

LOW

Threat Level

Priority /100

TBD

Exploited ITW

Monitor

CISA Status

Sources

🔵

HIGH-PRIORITY SECURITY ADVISORY — Priority Score: 43/100

CVSS 7.5 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-2026-55790 affecting composer craftcms/cms (CVSS 7.5, LOW severity). No confirmed in-the-wild exploitation at the time of writing; prioritize on exposure, privilege, and CVSS. Corroborated across 1 source(s): github_advisories. Verify all specifics against the primary sources linked below before acting.

Intelligence sources: github_advisories

🧬 Weakness Anatomy — CWE-79, the underlying flaw class

This vulnerability is classified as CWE-79: Cross-Site Scripting (XSS) in the primary record. The mechanics below are characteristic of this weakness class (per the MITRE CWE corpus), not a claim about a specific exploit observed against your environment.

How it's exploited	Attacker injects script into pages rendered to other users, running in their browser session to steal cookies/tokens or perform actions as the victim.
Detect & prevent	Context-aware output encoding; Content-Security-Policy; sanitize rich input. Detect via WAF signatures for script payloads and anomalous parameter content.

⚠️ Business Impact Analysis

⚠️ Privilege escalation — local attacker can become SYSTEM/root

🔗 Representative Attack Path

A typical attack path for this vulnerability class, mapped to MITRE ATT&CK. This is 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 craftcms/cms instances via Shodan, Censys, or targeted scanning	`TA0043`
2	Initial Access	Exploitation of CVE-2026-55790 in composer craftcms/cms	`T1190`
3	Privilege Escalation	Local privilege escalation to SYSTEM/root for full control	`T1068`
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 craftcms/cms (CVSS 7.5) represents a significant attack surface. SENTINEL APEX assesses exploitation to be technically feasible with moderate effort. Organizations running craftcms/cms in internet-facing or privileged positions face immediate risk.

SENTINEL APEX URGENCY: ELEVATED. Score: 43/100 LOW. Patch before exploitation activity begins.

🧠 Structured Intelligence Assessment

SENTINEL APEX analytical tradecraft separates verified fact from labeled assessment and states intelligence gaps explicitly. Confidence reflects evidentiary support, not certainty.

✔ Verified Facts

Affected CVE(s): CVE-2026-55790, CVE-2026-55790.
Affected technology: composer craftcms/cms.
CVSS base score of 7.5 assigned by an authoritative source.

🧩 Analyst Assessments

MEDIUM CONF Technical severity is assessed as high (CVSS 7.5); realized business impact depends on asset exposure and data classification.

❓ Intelligence Gaps

No confirmed public IOCs are available at report time; detection currently relies on behavioral analytics.
In-the-wild exploitation is unconfirmed as of this report.
Attribution to a specific threat actor is not established by the available evidence.
The source lacks sufficient technical detail for confident MITRE ATT&CK mapping.

🔮 Forward Outlook

LOW CONF Exploitation activity may emerge as technical details become public; monitor vendor advisories.

🎯 MITRE ATT&CK Mapping

Category	Mapping
Primary Tactic	Initial Access
Primary Technique	T1190 — Exploit Public-Facing Application
Sub-Technique	T1203 — Exploitation for Client Execution
Weakness (CWE)	CWE-79
Intel Type	🔴 CVE ANALYSIS
Source(s)	github_advisories

🔴 CVE Reference

CVE ID	Reference	Score
CVE-2026-55790	NVD →	7.5
CVE-2026-55790	NVD →	7.5

🔍 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-2026-55790 Exploitation Attempt — composer craftcms/cms
id: ca787313f36fbaba-64c3
status: experimental
description: Detects exploitation of CVE-2026-55790 in composer craftcms/cms. Priority: LOW. Score: 43/100
author: CYBERDUDEBIVASH SENTINEL APEX v4.0 (bivash@cyberdudebivash.com)
date: 2026-07-06
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-55790
    - https://blog.cyberdudebivash.in/
tags:
    - attack.initial_access
    - attack.t1190
    - cve-2026-55790
    - cve-2026-55790
logsource:
    category: webserver
detection:
    keywords:
        - 'CVE-2026-55790'
        - 'CVE-2026-55790'
        - 'cve-2026-55790'
    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_55790_Exploitation {
    meta:
        description = "Detects artifacts related to CVE-2026-55790 exploitation in composer craftcms/cms"
        author      = "CYBERDUDEBIVASH SENTINEL APEX v4.0"
        date        = "2026-07-06"
        severity    = "HIGH"
        cvss        = "7.5"
        priority    = "43/100"
        threat_level = "LOW"
        reference   = "https://nvd.nist.gov/vuln/detail/CVE-2026-55790"
    strings:
        $id_str  = "CVE-2026-55790" ascii nocase
        $product = "craftcms_cms" ascii nocase wide
    condition:
        any of them
}

🎯 Multi-Audience Intelligence Products

This single analysis is packaged for every stakeholder — from the boardroom to the SOC — plus a machine-readable feed for API and MSSP integration. Enterprise & SOC Pro subscribers receive these as structured deliverables.

🏛 Executive Advisory — CISO / Security Leadership

Affected CVE(s): CVE-2026-55790, CVE-2026-55790.
Affected technology: composer craftcms/cms.
CVSS base score of 7.5 assigned by an authoritative source.

Owner	Decision	Timeline
CISO / SOC Lead	Authorize response activation and detection deployment	Within 24h
Vulnerability Mgmt	Prioritize remediation/patching of composer assets	Within 7 days
Legal / Privacy	Assess regulatory notification obligations if in-scope data is at risk	Within 48h

📋 Board Brief

A high-severity cyber threat affects composer craftcms/cms.
Technical severity is rated 7.5/10.
Primary exposure is operational disruption, data loss, and potential regulatory liability (e.g. GDPR, NIS2, DORA, SOC 2) where in-scope systems are affected.
Mitigation depends on vendor guidance and compensating controls.
Recommended posture: authorize prioritized remediation and confirm detection coverage with the security team.

🛡 SOC Bulletin

Severity HIGH · Detection coverage: 0 technique(s) across behavioral analytics · 0 network rule(s)

P1: Sweep 14 days of telemetry for the mapped ATT&CK techniques.
P2: Update threat-intel platform and downstream detection feeds with confirmed indicators.

⎋ Machine-readable intelligence: this report is available as a structured JSON package (MITRE ATT&CK, IOCs, multi-platform detections, analyst assessments) at /api/intel/products/cve-2026-55790-composer-craftcms-cms.json — built for SIEM, SOAR, and MSSP integration.

🛡️ SOC Response Playbook

1IMMEDIATE (0-1hr): Identify all instances of craftcms/cms 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 craftcms/cms 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 craftcms/cms

📎 Intelligence References

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⚡ CYBERDUDEBIVASH SENTINEL APEX v4.0

Intelligence report generated by CYBERDUDEBIVASH SENTINEL APEX v4.0
Report ID: SENTINEL-CVE-2026-55790-2026-07-06 | Priority: 43/100 LOW | Sources: 1
© 2026 CYBERDUDEBIVASH PRIVATE LIMITED
Republication requires written attribution to CYBERDUDEBIVASH SENTINEL APEX

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