# React: Unauthenticated Remote Code Execution in React Server Components Advisory record · `GHSA-xqc2-xf4c-x3h3` - **Identifiers:** `GHSA-xqc2-xf4c-x3h3` · `CVE-2026-126187` - **State:** Confirmed - **Severity:** CVSS 9.5 Critical - **Critical:** Yes: CVSS 9+ - **Weakness (CWE):** [CWE-502](https://cwe.mitre.org/data/definitions/502.html) - **Tags:** [Insecure deserialization](https://agentprime.io/advisories/tag/deserialization.md) - **Published:** 10 Nov 2026 - **Updated:** 10 Nov 2026 - **Reviewed by a person:** No Published by the GitHub Advisory Database at 10 Nov 2026, 22:44 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Critical Critical, because: - CVSS score 9.5: 9.0 or more. How we decide what’s critical: ## Affected packages - `react-server-dom-parcel` (npm): affected `>=19.0.0, <19.0.9 || >=19.1.0, <19.1.10 || >=19.2.0, <19.2.9 || >=19.3.0, <19.3.1`; fixed in `19.0.9`, `19.1.10`, `19.2.9`, `19.3.1` - `react-server-dom-turbopack` (npm): affected `>=19.0.0, <19.0.9 || >=19.1.0, <19.1.10 || >=19.2.0, <19.2.9 || >=19.3.0, <19.3.1`; fixed in `19.0.9`, `19.1.10`, `19.2.9`, `19.3.1` - `react-server-dom-webpack` (npm): affected `>=19.0.0, <19.0.9 || >=19.1.0, <19.1.10 || >=19.2.0, <19.2.9 || >=19.3.0, <19.3.1`; fixed in `19.0.9`, `19.1.10`, `19.2.9`, `19.3.1` ## Not analysed yet We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check. ## Severity and exploitation - 9.5 Critical, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:N`, from CNA (GitHub_M) - **CISA KEV:** Not listed. - **EPSS:** No score. ## Timeline - 14 Oct 2026, 17:08 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/react/react/security/advisories/GHSA-xqc2-xf4c-x3h3) - 8 Nov 2026, 20:00 UTC: First seen by agentprime - 10 Nov 2026, 22:33 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-126187) - 10 Nov 2026, 22:44 UTC: [Confirmed by GitHub Advisory Database](https://github.com/advisories/GHSA-xqc2-xf4c-x3h3) - 10 Nov 2026, 23:00 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-xqc2-xf4c-x3h3) - 10 Nov 2026, 23:17 UTC: [Confirmed by NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-126187) ## Sources - [GitHub Advisory Database: GHSA-xqc2-xf4c-x3h3](https://github.com/advisories/GHSA-xqc2-xf4c-x3h3) - [OSV: GHSA-xqc2-xf4c-x3h3](https://osv.dev/vulnerability/GHSA-xqc2-xf4c-x3h3) - - - - - - - - - - - - Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code. ## Check whether this affects you A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet. - With the agentprime MCP server (), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .