How severe is CVE-2026-42211?

CVE-2026-42211 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-42211 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42211?

CVE-2026-42211 affects Shopify React-router. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42211?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42211 have an EU (EUVD) identifier?

Yes. CVE-2026-42211 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33999.

When was CVE-2026-42211 published?

CVE-2026-42211 was published on 2026-06-02 and last updated on 2026-06-17.

CVE-2026-42211

CVE-2026-42211 is a high-severity vulnerability in Shopify React-router with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (33rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-33999
Weakness: CWE-502
Affected product: Shopify React-router
Published: 2026-06-02
Last modified: 2026-06-17

Description

React Router is a router for React. In versions 7.0.0 through 7.14.1, when using Framework Mode, a combination of steps could potentially allow unauthorized remote code execution (RCE) through external requests. This attack requires the application code to have an existing prototype pollution vulnerability, which can then be leveraged in a 2-step attack where the second step triggers unauthorized RCE on the remote server. This does not impact applications using Declarative Mode (`<BrowserRouter>`) or Data Mode (`createBrowserRouter/<RouterProvider>`). This is patched in version 7.14.2.

Frequently asked questions

What is CVE-2026-42211?: React Router is a router for React. In versions 7.0.0 through 7.14.1, when using Framework Mode, a combination of steps could potentially allow unauthorized remote code execution (RCE) through external requests. This attack requires the application code to have an existing prototype pollution vulnerability, which can then be leveraged in a 2-step attack where the second step triggers unauthorized RCE on the remote server. This does not impact applications using Declarative Mode (`<BrowserRouter>`) or Data Mode (`createBrowserRouter/<RouterProvider>`). This is patched in version 7.14.2.
How severe is CVE-2026-42211?: CVE-2026-42211 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-42211 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42211?: CVE-2026-42211 affects Shopify React-router. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42211?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42211 have an EU (EUVD) identifier?: Yes. CVE-2026-42211 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33999.
When was CVE-2026-42211 published?: CVE-2026-42211 was published on 2026-06-02 and last updated on 2026-06-17.

References

https://github.com/remix-run/react-router/security/advisories/GHSA-49rj-9fvp-4h2h

Affected products (1)

cpe:2.3:a:shopify:react-router:*:*:*:*:*:node.js:*:*

More vulnerabilities in Shopify React-router

CVE-2026-21884 — High (CVSS 8.2): React Router is a router for React. In @remix-run/react version prior to 2.17.3. and react-router 7.0.0 through 7.11.0,…
CVE-2026-33245 — High (CVSS 8.0): React Router is a router for React. In versions 7.7.0 through 7.13.1, when using React Router's unstable React Server…
CVE-2026-22029 — High (CVSS 8.0): React Router is a router for React. In @remix-run/router version prior to 1.23.2 and react-router 7.0.0 through 7.11.0,…
CVE-2025-59057 — High (CVSS 7.6): React Router is a router for React. In @remix-run/react versions 1.15.0 through 2.17.0. and react-router versions 7.0.0…
CVE-2026-42342 — High (CVSS 7.5): React Router is a router for React. In versions 7.0.0 through 7.14.x of react-router and versions 2.10.0 through 2.17.4…
CVE-2026-34077 — High (CVSS 7.5): React Router is a router for React. In versions 7.7.0 through 7.13.1, when using React Router's unstable React Server…

All CVEs affecting Shopify React-router →

Other CWE-502 (Deserialization of Untrusted Data) vulnerabilities

CVE-2026-41104 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Planetary Computer Pro allows an unauthorized attacker to disclose…
CVE-2026-43633 — Critical (CVSS 10.0): HestiaCP versions 1.9.0 through 1.9.4 contain a deserialization vulnerability in the web terminal component caused by a…
CVE-2026-33819 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Bing allows an unauthorized attacker to execute code over a network.
CVE-2026-20131 — Critical (CVSS 10.0): A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could…
CVE-2026-25632 — Critical (CVSS 10.0): EPyT-Flow is a Python package designed for the easy generation of hydraulic and water quality scenario data of water…
CVE-2025-14931 — Critical (CVSS 10.0): Hugging Face smolagents Remote Python Executor Deserialization of Untrusted Data Remote Code Execution Vulnerability.…

Browse all CWE-502 (Deserialization of Untrusted Data) vulnerabilities →