CVE-2026-53666React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration
- 6.1MediumCVSS base score
- 0.42%Exploitation in 30 daysEPSS · top 63% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
React Router is a router for React. In versions 6.4.0 through 7.17.0, if application code was written in a way that allows attacker-supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for an attacker to trigger unexpected constructor execution on the client, which would in turn trigger an outbound network request. This is only possible with very specific (and unlikely) application-layer code. Note that this does not impact an application if it is using Declarative Mode. It only impacts Framework Mode and Data Mode applications that perform manual SSR/hydration. This issue has been fixed in version 7.18.0.
Timeline
ID reserved
By GitHub_M
- 48 days later
· 48 days later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| NVDNVD · Analyzed | 3.1 | Medium6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
- EPSS (exploitation in 30 days)
- 0.42% · top 63% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.1.
Affected products
- affected >= 6.4.0, < 7.18.0
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- npmreact-routerGHSA-337j-9hxr-rhxg (opens in a new tab)
References
References5
- https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg (opens in a new tab)x_refsource_CONFIRM
- https://github.com/remix-run/react-router/pull/15175 (opens in a new tab)x_refsource_MISC
- https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a (opens in a new tab)x_refsource_MISC
- https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180 (opens in a new tab)x_refsource_MISC
- https://github.com/remix-run/react-router/releases/tag/[email protected] (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-49628 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-337j-9hxr-rhxg (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-53666)Record last updated .