GHSA-49rj-9fvp-4h2h CVE-2026-42211
React Router's vendored turbo-stream v2 allows arbitrary constructor invocation via TYPE_ERROR deserialization leading to Unauth RCE
- Severity
- 8.1 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.42%
- Chance of exploitation in the next 30 days. Higher than 35.94% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-502 Deserialization of Untrusted Data
- Fix
7.14.2- Upgrade react-router to this version or later
Description
When using React Router v7 in Framework Mode, there exists a combination of steps that could potentially allow unauthorized RCE through external requests. This first requires the application code to have an existing prototype pollution vulnerability. This can be leveraged into a 2-step attack in which the second step can trigger unauthorized RCE on the remote server.
[!NOTE] This does not impact your React Router application if you are using Declarative Mode (
<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>).
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| react-router | >= 7.0.0, <= 7.14.1 |
No fix yet |
| react-router | >= 7.0.0, < 7.14.2 |
7.14.2 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
react-router npm → 7.14.2
- npm
npm install react-router@7.14.2- yarn
yarn add react-router@7.14.2- pnpm
pnpm add react-router@7.14.2
Severity breakdown
CVSS 3.1 8.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-502: Deserialization of Untrusted Data
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
How to prevent it
- Architecture and Design, Implementation: If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
- Implementation: When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
- Implementation: Explicitly define a final object() to prevent deserialization.
- Architecture and Design, Implementation: Make fields transient to protect them from deserialization. An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.
- Implementation: Avoid having unnecessary types or gadgets (a sequence of instances and method invocations that can self-execute during the deserialization process, often found in libraries) available that can be leveraged for malicious ends. This limits the potential for unintended or unauthorized types and gadgets to be leveraged by the attacker. Add only acceptable classes to an allowlist. Note: new gadgets are constantly being discovered, so this alone is not a sufficient mitigation.
- Architecture and Design, Implementation: Employ cryptography of the data or code for protection. However, it's important to note that it would still be client-side security. This is risky because if the client is compromised then the security implemented on the client (the cryptography) can be bypassed.
- Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
References
Advisories
Packages
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-qwww-vcr4-c8h2 React Router: RSC Mode CSRF Bypass Allows Action Execution Before 400 Response | High | Also affects react-router |
| GHSA-chx6-hx7r-mcp5 React Router: Unauthenticated Denial of Service via Inefficient Route Matching | High | Also affects react-router |
| GHSA-wrjc-x8rr-h8h6 React Router: Open redirect via backslash in <Link> and useNavigate (CVE-2025-68470 bypass) | Medium | Also affects react-router |
| GHSA-jjmj-jmhj-qwj2 React Router: Open redirect leading to XSS | Medium | Also affects react-router |
| GHSA-h8fp-f39c-q6mh React Router: RSCErrorHandler Missing Protocol Validation (XSS) | Medium | Also affects react-router |
| GHSA-337j-9hxr-rhxg React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration | Medium | Also affects react-router |
| GHSA-84g9-w2xq-vcv6 React Router: Potential CSRF via PUT/PATCH/DELETE document requests | Low | Also affects react-router |
| GHSA-8x6r-g9mw-2r78 React Router vulnerable to DoS via unbounded path expansion in __manifest endpoint | High | Also affects react-router |
Credits: SM41ldRag0n
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