GreyNoise Labs Weekly OAST Report: MCP Server Command Injection and React2Shell Exploitation Campaigns – Week Ending 2026-01-09
Source Community Curated
Exploited in the wild · KEV due 12 Dec 2025 · public exploit available (Metasploit, Exploit-DB) : block it and hunt for it in your logs now.
Data as of 11 Jan 2026, 15:45 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else.
Exploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 3 Dec 2025
Detectable: evidence found.
nuclei template: React Server Components - Remote Code Execution
Weaponised: evidence found.
1 Metasploit module · 1 Exploit-DB entry, 127 days after disclosure
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 2 days after disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by Meta
, 117 days before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 14 minutes after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed · ransomware use known
, 2 days after disclosure
KEV remediation due
US federal deadline
, 9 days after disclosure
First Exploit-DB entry (opens in a new tab)
React Server 19.2.0 - Remote Code Execution
, 127 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.
What to do
Integrate the provided IOCs and JA4 fingerprints into network detection tools and SIEMs to identify and block related scanning and exploitation attempts. Monitor for the described payload patterns and OAST callback domains, and apply relevant patches or mitigations for CVE-2025-55182 and MCP server vulnerabilities.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Metareact-server-dom-webpack | Affected
| Fixed in– |
| Metareact-server-dom-turbopack | Affected
| Fixed in– |
| Metareact-server-dom-parcel | Affected
| Fixed in– |
npmreact-server-dom-parcelpkg:npm/react-server-dom-parcelOther threats | Affected
| Fixed in– |
npmreact-server-dom-turbopackpkg:npm/react-server-dom-turbopackOther threats | Affected
| Fixed in– |
npmreact-server-dom-webpackpkg:npm/react-server-dom-webpackOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
This GreyNoise Labs report provides detailed analysis of out-of-band interaction domain (OAST) activity observed during January 3-9, 2026, identifying three distinct campaigns exploiting vulnerabilities including MCP server command injection and React2Shell (CVE-2025-55182). It includes comprehensive telemetry such as JA4 fingerprint clusters, payload samples, IOC tables, and detection recommendations, offering actionable intelligence for defenders.