Full Report
React is a JavaScript library used to build interactive user interfaces using reusable components. React Server Components (RSC) extend this model by allowing certain components and logic to run on the server, rather than in the browser. Frameworks like next.js heavily rely on RSC, making security flaws in this area especially impactful. Vulnerability Overview CVE-2025-55182 […] The post React2Shell (CVE-2025-55182): RSC Flight Decoder Remote Code Execution appeared first on Blogs on Information Technology, Network & Cybersecurity | Seqrite.
Analysis Summary
# Vulnerability: React2Shell (CVE-2025-55182): RSC Flight Decoder Remote Code Execution
## CVE Details
- CVE ID: CVE-2025-55182
- CVSS Score: Critical (Specific score not provided, but described as Critical)
- CWE: Insufficient Validation of Untrusted Data (Inferred from prototype pollution/unsafe deserialization leading to RCE)
## Affected Systems
- Products: React Server Components (RSC), Frameworks utilizing RSC (e.g., Next.js)
- Versions: Not explicitly specified in the summary, but implied to be versions prior to the patch.
- Configurations: Servers processing untrusted Flight protocol payloads via RSC endpoints.
## Vulnerability Description
CVE-2025-55182 is a Remote Code Execution (RCE) vulnerability found in the decoding logic of the React Server Components (RSC) Flight protocol. The flaw resides in how React resolves object properties when decoding incoming Flight payloads. The decoder uses attacker-supplied property names to access object values without performing an explicit check (like `hasOwnProperty`). This allows an attacker to exploit JavaScript's default prototype chain lookup behavior. By controlling the property key (`key` in `object[key]`), an attacker can access inherited prototype properties, enabling gadget-based escalation leading to arbitrary code execution on the server.
## Exploitation
- Status: Not explicitly stated if exploited in the wild, but the mechanism is detailed.
- Complexity: Implied Low/Medium due to direct RCE capability from an unauthenticated request.
- Attack Vector: Network (Requires sending a crafted POST request to an RSC endpoint).
## Impact
- Confidentiality: High (Potential total compromise via RCE)
- Integrity: High (Potential total compromise via RCE)
- Availability: High (Potential denial of service or complete system takeover)
## Remediation
### Patches
- Patches are available that synchronize server-side and client-side Flight protocol handling.
- The fix involves adding explicit **`hasOwnProperty`** checks before returning values from module export objects during deserialization, preventing unsafe prototype-chain access.
- Improvements were also made to multipart payload decoding robustness with added error handling.
### Workarounds
- No specific workarounds were detailed in the provided text, aside from applying the patch.
## Detection
- Detection methods focus on monitoring incoming network traffic to RSC-enabled endpoints for malformed or suspicious Flight protocol POST requests.
- **Indicators of Compromise (IOC):** Look for unexpected execution flows or RCE artifacts resulting from the deserialization step.
- **Detection Tools:** Web Application Firewalls (WAFs) or runtime application self-protection (RASP) tools capable of inspecting request bodies intended for RSC/Server Function routes.
## References
- Vendor Advisories: Implied patch release by the React core team addressing CVE-2025-55182.
- Relevant Links: hxxps://www.seqrite.com/blog/react2shell-cve-2025-55182-rsc-flight-decoder-remote-code-execution/