December 2025 witnessed a dramatic 120% increase in high-impact vulnerabilities, with Recorded Future's Insikt Group® identifying 22 vulnerabilities requiring immediate remediation, up from 10 in November. The month was dominated by widespread exploitation of Meta's React Server Components flaw.

What security teams need to know:

• React2Shell pandemonium: CVE-2025-55182 triggered a global exploitation wave with multiple threat actors deploying diverse malware families
• China-nexus exploitation intensifies: Earth Lamia, Jackpot Panda, and UAT-9686 leveraged critical flaws for espionage operations
• Public exploits proliferate: Eleven of 22 vulnerabilities have proof-of-concept code available, accelerating exploitation timelines
• Legacy vulnerabilities resurface: CISA added 2018-2022 era flaws to its Known Exploited Vulnerabilities (KEV) catalog, highlighting persistent patch gaps

Bottom line: December's surge reflects both new zero-days and renewed interest in legacy vulnerabilities. React2Shell alone demonstrates how quickly modern web frameworks can become global attack vectors.

Quick Reference Table

All 22 vulnerabilities below were actively exploited in December 2025.

Table 1: List of vulnerabilities that were actively exploited in December based on Recorded Future data (Source: Recorded Future)

Key Trends in December 2025

Affected Vendors

• Fortinet continued vulnerability concerns with two critical authentication bypass flaws
• Google faced three vulnerabilities across Android (2) and Chromium (1) platforms
• Microsoft dealt with a Windows kernel use-after-free vulnerability
• Meta experienced the month's most impactful vulnerability with React2Shell
• Additional affected vendors: Array Networks, Gogs, Gladinet, ASUS, Cisco, Apple, SonicWall, WatchGuard, MongoDB, Digiever, Sierra Wireless, OSGeo, RARLAB, D-Link, and OpenPLC

Most Common Weakness Types

• CWE-22 – Path Traversal
• CWE-347 – Improper Verification of Cryptographic Signature
• CWE-416 – Use After Free
• CWE-434 – Unrestricted Upload of File with Dangerous Type
• CWE-787 – Out-of-bounds Write

Threat Actor Activity

React2Shell exploitation dominated December’s CVE activity:

• Threat actors observed to have exploited this vulnerability:
  • China-nexus actors Earth Lamia and Jackpot Panda
  • China-linked clusters UNC6600, UNC6586, UNC6588, UNC6603, and UNC6595
  • North Korea-linked and financially motivated groups
• Observed payloads included EtherRAT, PeerBlight, CowTunnel, ZinFoq, Kaiji variants, Zndoor, RondoDox, MINOCAT, SNOWLIGHT, COMPOOD, HISONIC, ANGRYREBEL.LINUX, and Weaxor ransomware (using a Cobalt Strike stager)
• Infrastructure connections to HiddenOrbit relay infrastructure and GobRAT relay component

Additional activity:

• UAT-9686 exploited Cisco Secure Email Gateway (CVE-2025-20393), deploying AquaShell, AquaPurge, and AquaTunnel
• Unknown actors leveraged Gogs vulnerability (CVE-2025-8110) for Supershell malware deployment

Priority Alert: Active Exploitation

These vulnerabilities demand immediate attention due to confirmed widespread exploitation.

CVE-2025-55182 | Meta React Server Components (React2Shell)

Risk Score: 99 (Very Critical) | CISA KEV: Added December 5, 2025

Why this matters: Unauthenticated RCE affects React and Next.js, among the world's most popular web frameworks. Multiple threat actors are actively exploiting vulnerable instances with diverse malware payloads.

Affected versions:

• React packages: react-server-dom-webpack, react-server-dom-parcel, react-server-dom-turbopack (19.0.0, 19.1.0, 19.1.1, and 19.2.0)
• Next.js: 15.x, 16.x, and Canary builds from 14.3.0-canary.77
• Also affects: React Router, Waku, RedwoodSDK, Parcel, Vite RSC plugin

Immediate actions:

• Upgrade React to 19.0.3, 19.1.4, or 19.2.3 immediately
• Update Next.js to 16.0.7, 15.5.7, 15.4.8, 15.3.6, 15.2.6, 15.1.9, or 15.0.5
• Monitor for unusual multipart/form-data POST requests consistent with Next.js Server Actions / RSC endpoints
• Check logs for E{"digest" error patterns indicating exploitation attempts
• Review server processes for unexpected Node.js child processes

Exposure: ~310,500 Next.js instances on Shodan (US, India, Germany, Japan, Australia)

CVE-2025-20393 | Cisco Secure Email Gateway

Risk Score: 99 (Very Critical) | Active exploitation by UAT-9686

Why this matters: Chinese threat actors are actively compromising email security infrastructure to establish persistent access and pivot into internal networks.

Affected products: Cisco Secure Email Gateway and Secure Email and Web Manager running AsyncOS

Immediate actions:

• Apply Cisco's security updates immediately
• Monitor Spam Quarantine web interface access logs
• Check for modifications to /data/web/euq_webui/htdocs/index.py
• Hunt for AquaShell, AquaPurge, and AquaTunnel indicators
• Review outbound connections to suspicious IPs

Known C2 infrastructure: 172.233.67.176, 172.237.29.147, 38.54.56.95 (inactive)

CVE-2025-14611 | Gladinet CentreStack/Triofox

Risk Score: 99 (Very Critical) | CISA KEV: Added December 16, 2025

Why this matters: Hard-coded cryptographic keys enable unauthenticated file reads, including sensitive configuration files. Active exploitation observed in the wild.

Affected versions: All versions before 16.12.10420.56791

Immediate actions:

• Upgrade to version 16.12.10420.56791 or later
• Audit file access logs for unauthorized reads
• Review Access Tickets for year 9999 timestamps
• Check for web.config exfiltration attempts
• Rotate all stored credentials and API keys

Technical Deep Dive: Exploitation Analysis

React2Shell Exploitation (CVE-2025-55182)

React2Shell represents a fundamental flaw in React Server Components' Flight protocol implementation:

• Insecure deserialization – Server accepts malformed Flight payloads without validation
• Protocol confusion – Attacker-controlled data influences server-side execution
• Unauthenticated access – No authentication required for RSC endpoints
• Wide impact – Affects the entire React ecosystem using Server Components

Analysis of exploitation activity from Insikt Group observations:

• Payloads delivered via wget to download secondary stages
• Active malware hosts serving RondoDox
• Operators using public PoCs with minimal modifications

Why this matters: The combination of a popular framework, simple exploitation, and high impact created perfect conditions for mass compromise. Organizations must assume exposure if running vulnerable versions.

Insikt Group created a Nuclei template for safe detection, available to Recorded Future customers. The template identifies vulnerable instances without triggering exploitation.

UAT-9686 Cisco Campaign (CVE-2025-20393)

Sophisticated espionage operation: Chinese threat actors demonstrated advanced tradecraft:

• Initial access via Spam Quarantine interface exploitation
• Persistence through Python backdoor embedded in legitimate UI files
• Log manipulation with AquaPurge to remove forensic evidence
• Tunneling via AquaTunnel and Chisel for internal pivoting

Why this matters: Email gateways represent critical infrastructure. Compromise enables interception of sensitive communications and lateral movement into protected networks.

MongoBleed Information Disclosure (CVE-2025-14847)

Memory leak through protocol confusion: The vulnerability exploits mismatched length fields in Zlib-compressed headers:

• Attacker sends crafted BSON documents with falsified lengths
• MongoDB's parser reads beyond intended boundaries
• Uninitialized heap memory exposed in error messages
• Potential for credential and key material exposure

Why this matters: Database servers often contain authentication tokens, API keys, and sensitive configuration in memory. Even read-only access can enable further attacks.

Detection & Remediation Resources

Nuclei Templates from Insikt Group®

Recorded Future customers can access Nuclei templates for:

• CVE-2025-55182 (React2Shell) - Safe deserialization check without exploitation

Note: All templates perform non-intrusive detection only.

Recorded Future Product Integrations

• Vulnerability Intelligence – Track exploitation trends across December's 22 critical flaws
• Attack Surface Intelligence – Identify exposed React, MongoDB, and Cisco assets
• Third-Party Intelligence – Assess supply chain exposure to framework vulnerabilities

December 2025 Summary

Framework vulnerabilities go viral. React2Shell demonstrated how modern web frameworks can become global attack vectors within days of disclosure.

Legacy flaws find new life. The addition of 2018-2022 vulnerabilities to CISA's KEV catalog shows threat actors mining old CVEs for unpatched targets.

Nation-state actors accelerate timelines. Chinese and North Korean groups deployed sophisticated campaigns within hours of vulnerability disclosure.

Take Action

Ready to see how Recorded Future can help your team track mass exploitation, prioritize framework updates, and detect emerging threats? Explore our demo center for live examples. Dive deeper with Insikt Group research for technical threat intelligence.

About Insikt Group®:

Recorded Future's Insikt Group® combines elite security researchers, data scientists, and intelligence analysts to deliver actionable threat intelligence. Our team tracks global vulnerability exploitation to help organizations stay ahead of emerging threats.