How severe is CVE-2026-23864?

CVE-2026-23864 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-23864?

CVE-2026-23864 affects the following packages: react-server-dom-parcel (npm), react-server-dom-turbopack (npm), react-server-dom-webpack (npm), react-server-dom-turbopack (npm), react-server-dom-parcel (npm), react-server-dom-parcel (npm), react-server-dom-webpack (npm), react-server-dom-webpack (npm), and 1 more. Ecosystems affected: npm.

How do I fix CVE-2026-23864?

Update react-server-dom-parcel to 19.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23864 is resolved across your whole dependency graph.

How do I detect CVE-2026-23864 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for react-server-dom-parcel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-23864 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-23864?

O3 pinpoints whether CVE-2026-23864 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-23864 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-23864 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-23864?

CVE-2026-23864 has an EPSS (Exploit Prediction Scoring System) score of 1.5%, placing it in the 70th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-23864?

CVE-2026-23864 is classified as Uncontrolled Resource Consumption (CWE-400), Deserialization of Untrusted Data (CWE-502). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-23864 published, and has it been updated?

CVE-2026-23864 was published on January 26, 2026 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

CVE-2026-23864

HIGH

React Server Components have multiple Denial of Service Vulnerabilities

Also known asGHSA-83fc-fqcc-2hmg

Published

Jan 26, 2026

Updated

Apr 10, 2026

Affected

9 pkgs

Patched

9 / 9

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

1.5%probability of exploitation in next 30 days

Lower Risk70th percentile-0.51%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

9 pkgs affected

📦react-server-dom-parcel📦react-server-dom-turbopack📦react-server-dom-webpack📦react-server-dom-turbopack📦react-server-dom-parcel📦react-server-dom-parcel📦react-server-dom-webpack📦react-server-dom-webpack+1 more

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Multiple denial of service vulnerabilities exist in React Server Components, affecting the following packages: react-server-dom-parcel, react-server-dom-turbopack, react-server-dom-webpack.

The vulnerabilities are triggered by sending specially crafted HTTP requests to Server Function endpoints, and could lead to server crashes, out-of-memory exceptions or excessive CPU usage; depending on the vulnerable code path being exercised, the application configuration and application code.

Strongly consider upgrading to the latest package versions to reduce risk and prevent availability issues in applications using React Server Components.

Affected Packages

9 total 9 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`react-server-dom-parcel`	≥ 19.0.0&&< 19.0.4	19.0.4
📦npm	`react-server-dom-turbopack`	≥ 19.1.0-canary-7130d0c6-20241212&&< 19.1.5	19.1.5
📦npm	`react-server-dom-webpack`	≥ 19.2.0-canary-63779030-20250328&&< 19.2.4	19.2.4
📦npm	`react-server-dom-turbopack`	≥ 19.0.0&&< 19.0.4	19.0.4
📦npm	`react-server-dom-parcel`	≥ 19.1.0-canary-7130d0c6-20241212&&< 19.1.5	19.1.5
📦npm	`react-server-dom-parcel`	≥ 19.2.0-canary-63779030-20250328&&< 19.2.4	19.2.4

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for react-server-dom-parcel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update react-server-dom-parcel to 19.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23864 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-23864 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-23864. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Multiple denial of service vulnerabilities exist in React Server Components, affecting the following packages: react-server-dom-parcel, react-server-dom-turbopack, react-server-dom-webpack. The vulnerabilities are triggered by sending specially crafted HTTP requests to Server Function endpoints, and could lead to server crashes, out-of-memory exceptions or excessive CPU usage; depending on the vulnerable code path being exercised, the application configuration and application code. Strongly consider upgrading to the latest package versions to reduce risk and prevent availability issues in ap

O3 Security · Impact-Aware SCA

Is CVE-2026-23864 in your dependencies?

O3 detects CVE-2026-23864 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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