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Fencer Intel
critical 9.5

CVE-2026-126187 in the critical feed json

React: Unauthenticated Remote Code Execution in React Server Components

published 28d ago modified yesterday also GHSA-xqc2-xf4c-x3h3 , EUVD-2026-123052

cvss
9.5
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

React is a JavaScript library for building user interfaces. From 19.0.0 until 19.0.9, 19.1.10, 19.2.9, and 19.3.1, the react-server-dom-webpack, react-server-dom-parcel, and react-server-dom-turbopack packages are vulnerable to unauthenticated remote code execution through crafted payloads targeting frameworks that support React Server Components. The vulnerability only affects extremely rare cases where responses transport multiple typed arrays and an attacker-controlled value. Applications whose React code does not use a server are not affected. Applications that do not use a framework, bundler, or bundler plugin that supports React Server Components are not affected. This issue is fixed in versions 19.0.9, 19.1.10, 19.2.9, and 19.3.1.

Patch / fix

  • npm react-server-dom-parcel 19.0.9, 19.1.10, 19.2.9, 19.3.1
  • npm react-server-dom-turbopack 19.0.9, 19.1.10, 19.2.9, 19.3.1
  • npm react-server-dom-webpack 19.0.9, 19.1.10, 19.2.9, 19.3.1

Is CVE-2026-126187 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

1.76% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 9.5 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
CNA 4.0 9.5 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
npm react-server-dom-parcel
>=19.0.0, <19.0.9
>=19.1.0, <19.1.10
>=19.2.0, <19.2.9
>=19.3.0, <19.3.1
19.0.9
19.1.10
19.2.9
19.3.1
npm react-server-dom-turbopack
>=19.0.0, <19.0.9
>=19.1.0, <19.1.10
>=19.2.0, <19.2.9
>=19.3.0, <19.3.1
19.0.9
19.1.10
19.2.9
19.3.1
npm react-server-dom-webpack
>=19.0.0, <19.0.9
>=19.1.0, <19.1.10
>=19.2.0, <19.2.9
>=19.3.0, <19.3.1
19.0.9
19.1.10
19.2.9
19.3.1

Affected products

  • react react

Classification

Weakness
  • CWE-502 Deserialization of Untrusted Data
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of react/react published their own advisory on GitHub. Reviewed sources take precedence over it.