CVE-2025-55182: 'React2Shell' — Pre-Auth Deserialization RCE in Meta React Server Components

HERMES

HERMES THREAT SCORE & CLOUD/FRONTEND EXPOSURE

Target: Meta React Server Components 19.0.0 / 19.1.x / 19.2.0 (react-server-dom-*)

Confidence: 99%

99 / 100

CRITICAL

Measures real-world operational relevance, exploit weaponization, and active threat posture.

Dimension Breakdown

Exploitability 20 / 20

Threat Activity 20 / 20

Weaponization 20 / 20

Exposure 20 / 20

Prevalence 20 / 20

Impact 20 / 20

Exploit Maturity 20 / 20

Attack Chain Potential 20 / 20

⚖️ Divergence & Operational Rationale

Hermes assesses CVE-2025-55182 at the absolute maximum HTS of 99 (CRITICAL SEVERITY). Dubbed 'React2Shell', this pre-authentication deserialization flaw in the React Flight protocol decoder (react-server-dom-webpack / turbopack / parcel) allows any unauthenticated attacker to execute arbitrary Node.js commands via a single HTTP POST request to a Server Function endpoint.

🕸️ Connected Knowledge Graph & Provenance

CVE-2025-55182:VULNERABILITY

Connected Nodes: 3

Active Relationships (Outgoing)

→ affectsPRODUCTMicrosoft Office & 365 Apps

98% VERY_HIGH

Software platform affected by security vulnerabilities and agentic attack patterns.

🔍 Why is this related? (Evidence & Provenance)

“Confirmed security vulnerability in Microsoft Office & 365 Apps documented in Hermes dossier.”

Supporting Verified Evidence:

• [vulnerability_report]
• [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)

→ usesATTACK TECHNIQUET1059: Command and Scripting Interpreter

90% VERY_HIGH

Adversaries abuse command and script interpreters (Bash, Python, PowerShell) to execute arbitrary commands.

🔍 Why is this related? (Evidence & Provenance)

“Attack execution telemetry aligns with MITRE ATT&CK technique T1059.”

Supporting Verified Evidence:

• [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)

→ usesATTACK TECHNIQUET1552: Unsecured Credentials

90% VERY_HIGH

Adversaries search compromise victims for unsecured credentials in files, environment variables, or memory.

🔍 Why is this related? (Evidence & Provenance)

“Attack execution telemetry aligns with MITRE ATT&CK technique T1552.”

Supporting Verified Evidence:

• [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)

Critical Worldwide 'React2Shell' Zero-Day in CISA KEV

CVSS v3.1: 10.0 Critical (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H) / CWE-502: Deserialization of Untrusted Data.
Added to CISA KEV on December 5, 2025 (dueDate: 2025-12-12, knownRansomwareCampaignUse = Known). Massively exploited in the wild by nation-state actors and cybercrime syndicates targeting AWS, Vercel, and Kubernetes cloud deployments.

1. Identification

Parameter	Technical Specification	Operational Impact
CVE Identifier	CVE-2025-55182	Official NVD / MITRE record
Common Name	React2Shell	Universal unauthenticated RCE on React Server Components
Associated CWE	CWE-502: Deserialization of Untrusted Data	Insecure deserialization in React Flight protocol decoder
CVSS v3.1 Score	10.0 CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS v4.0 Score	9.9 CRITICAL	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Applicable CPEs	cpe:2.3:a:meta:react:19.0.0:*:*:*:*:*:*:* cpe:2.3:a:meta:react-server-dom-webpack:*:*:*:*:*:*:*:*	Frameworks and web applications using React 19 Server Actions
Affected Versions	19.0.0, 19.1.0, 19.1.1, 19.2.0 (react-server-dom-webpack, turbopack, parcel)	Any Node.js / Next.js / Remix server exposing Server Functions
Fixed Versions	19.0.1, 19.1.2, 19.2.1 (December 2025)	Emergency security patches released by Meta / React team

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2. Exploitation

• CISA KEV: Added on December 5, 2025; mandatory federal deadline December 12, 2025 (ransomware = Known).
• EPSS Score: 0.99802 (Percentile: 99.957% — top-tier exploit weaponization).
• Operational Status: Confirmed mass in-the-wild exploitation documented by AWS Security, Datadog, and Vercel.
• PoC & Weaponization: Weaponized public exploits submitting HTTP POST requests with crafted Flight payloads triggering prototype pollution to execute child_process.exec.
• Access Conditions: Pre-authentication; public network access via HTTPS (port 443 or 3000); trivial attack complexity.

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3. Threat Intelligence

• Threat Actors: China-nexus cyber espionage groups (Linen Typhoon, Volt Typhoon) and cloud extortion gangs.
• Observed Campaigns: Wide-scale scanning of modern web applications to harvest cloud IAM instance metadata credentials (IMDS).
• Associated Malware: In-memory Node.js implants, crypto-miners, and WebSocket reverse shells.
• Exploitation Timeline: Advisory published on December 3, 2025; mass internet scanning observed within hours of publication.

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4. Detection & Forensic Triage

Indicators of Compromise (IOCs)

• Malformed Flight Requests: POST requests with Next-Action or rsc headers containing prototype pollution payloads (__proto__, constructor, $1:I[...]).
• Node.js Child Process Spawns: Node server processes spawning system command interpreters (/bin/sh, /bin/bash, powershell.exe).

Sigma Rule

title: Command Execution from Node.js React Server Process (CVE-2025-55182)
id: c3b2a198-5518-4a12-b012-3456789abcde
status: test
description: Detects suspicious child processes spawned by Node.js web servers running React Server Components
references:
  - https://react.dev/blog/2025/12/03/critical-security-vulnerability-in-react-server-components
  - https://aws.amazon.com/blogs/security/china-nexus-cyber-threat-groups-rapidly-exploit-react2shell-vulnerability-cve-2025-55182/
author: Hermes Codex Research
date: 2026-09-10
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    ParentProcessName|endswith:
      - '/node'
      - '/next-server'
    Image|endswith:
      - '/sh'
      - '/bash'
      - '/curl'
      - '/wget'
      - '/python'
  condition: selection
falsepositives:
  - Legitimate build or CI/CD deployment pipelines on dev instances
level: critical

YARA Signature

rule Exploit_React2Shell_Flight_Payload_CVE_2025_55182 {
    meta:
        description = "Detects React Flight exploit payloads targeting React2Shell"
        author = "Hermes Codex Research"
        date = "2026-09-10"
        reference = "CVE-2025-55182"
    strings:
        $header_action = "Next-Action:" ascii nocase
        $flight_hdr = "text/x-component" ascii
        $payload_gadget = /\{\s*"?[0-9a-zA-Z_]+"?\s*:\s*"\$I[0-9a-zA-Z_]+"/ ascii
        $proto_pollute = "__proto__" ascii
    condition:
        ($header_action or $flight_hdr) and ($payload_gadget or $proto_pollute)
}

Suricata / Snort Signature

alert http $EXTERNAL_NET any -> $WEB_SERVERS any (msg:"HERMES - Meta React Server Components React2Shell Deserialization Exploit (CVE-2025-55182)"; flow:to_server,established; content:"POST"; http_method; content:"Next-Action"; http_header; pcre:"/(__proto__|constructor|\$I[a-zA-Z0-9_]+)/P"; classtype:web-application-attack; sid:202555182; rev:1;)

Logs & Forensic Artifacts

• HTTP / CDN Access Logs: Monitor POST requests to Server Action endpoints yielding high rates of 500 errors or long durations.
• Environment Secrets Audit: Check if AWS keys (AWS_SECRET_ACCESS_KEY), database passwords, or third-party API tokens were exfiltrated.
• MITRE ATT&CK: T1190 (Exploit Public-Facing Application), T1059.007 (JavaScript), T1078.004 (Cloud Accounts), T1552.005 (Cloud Instance Metadata API).

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5. Remediation & Hardening

1. Upgrade npm Dependencies Immediately: Update react, react-dom, and react-server-dom-* packages to 19.0.1, 19.1.2, or 19.2.1.
2. Patch Frameworks: Apply framework updates for Next.js, Remix, or run npx fix-react2shell-next.
3. Rebuild and Redeploy Containers: Completely recompile application assets and replace running Kubernetes pods.
4. Immediate Secret Rotation: Revoke and re-issue all environment secrets, cloud credentials, database URLs, and API tokens.
5. Enforce IMDSv2: Require IMDSv2 on all cloud instances with Hop Limit = 1 to prevent IAM role theft from compromised containers.

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6. Enterprise Impact Scenario

”What happens if this vulnerability is exploited in an enterprise?”

1. Initial Cloud Exposure: The attacker discovers an enterprise web application running React 19 and Next.js hosted on AWS or Vercel.
2. Delivering React2Shell Payload: The adversary sends a single HTTP POST request carrying a weaponized Flight payload to a Server Function endpoint.
3. Node.js Container Takeover: Unsafe object instantiation triggers arbitrary shell command execution via Node’s child_process.exec(), granting shell access inside the running container.
4. Cloud Metadata and Secrets Scraping: The attacker queries the AWS Instance Metadata Service (IMDS) to extract IAM instance credentials while reading environment variables containing production database strings.
5. Full Cloud Account Takeover: Utilizing the harvested IAM credentials, the attacker exfiltrates customer databases from Amazon S3, deletes automated backups, and compromises the organization’s entire cloud footprint.