CVE-2026-53666

MEDIUMPre-NVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 77% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
6.1
EG Score
6.1(medium)
EG Risk
28(Track)
EG Risk 28/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity61% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

July 23, 2026

Last Modified

August 3, 2026

Advisory Details (5)

Auto-updated Jul 27, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

v7.18.0

Patch available: remix-run/react-router [email protected]

https://github.com/remix-run/react-router/releases/tag/[email protected]
generic

react-router/CHANGELOG.md at main · remix-run/react-router · GitHub

https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180
github_commit Patch Available

commit 9d22943fd46c (remix-run/react-router)

Patch available: remix-run/react-router [email protected] (contains commit 9d22943fd46c)

https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a
github_pr Patch Available

Use turbo stream for framework hydration errors

Patch available: remix-run/react-router [email protected] (PR #15175 merged 2026-06-11)

https://github.com/remix-run/react-router/pull/15175
github Patch Available

Arbitrary client-side constructor injection via React Router SSR Hydration · Advisory · remix-run/react-router · GitHub

https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg

Vendor Advisories for CVE-2026-53666(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
react-router—7.18.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 55× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-25 11:32 UTCEG score recompute
  3. 2026-08-24 13:02 UTCEG score recompute
  4. 2026-08-23 14:33 UTCEG score recompute
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-22 16:04 UTCEG score recompute
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-21 17:32 UTCEG score recompute
  9. 2026-08-20 22:55 UTCEPSS rescore
  10. 2026-08-19 20:31 UTCEG score recompute
  11. 2026-08-19 17:04 UTCEPSS rescore
  12. 2026-08-18 18:57 UTCEG score recompute
  13. 2026-08-18 13:48 UTCEPSS rescore
  14. 2026-08-17 15:37 UTCEG score recompute
  15. 2026-08-17 13:47 UTCEPSS rescore
  16. 2026-08-16 17:08 UTCEG score recompute
  17. 2026-08-16 14:56 UTCEPSS rescore
  18. 2026-08-16 02:14 UTCEPSS rescore
  19. 2026-08-15 18:39 UTCEG score recompute
  20. 2026-08-15 01:30 UTCEPSS rescore
  21. 2026-08-14 20:09 UTCEG score recompute
  22. 2026-08-13 22:00 UTCEPSS rescore
  23. 2026-08-12 23:09 UTCEG score recompute
  24. 2026-08-12 13:51 UTCEPSS rescore
  25. 2026-08-12 00:40 UTCEG score recompute
Show 31 more
  1. 2026-08-11 02:10 UTCEG score recompute
  2. 2026-08-11 00:00 UTCEPSS rescore
  3. 2026-08-10 03:41 UTCEG score recompute
  4. 2026-08-09 13:46 UTCEPSS rescore
  5. 2026-08-09 05:12 UTCEG score recompute
  6. 2026-08-08 16:37 UTCEPSS rescore
  7. 2026-08-08 06:43 UTCEG score recompute
  8. 2026-08-07 08:13 UTCEG score recompute
  9. 2026-08-06 13:47 UTCEPSS rescore
  10. 2026-08-06 09:44 UTCEG score recompute
  11. 2026-08-05 19:17 UTCEPSS rescore
  12. 2026-08-05 11:13 UTCEG score recompute
  13. 2026-08-04 15:10 UTCEPSS rescore
  14. 2026-08-04 12:43 UTCEG score recompute
  15. 2026-08-04 10:39 UTCEPSS rescore
  16. 2026-08-03 14:13 UTCEG score recompute
  17. 2026-08-03 10:36 UTCEPSS rescore
  18. 2026-08-02 09:00 UTCEG score recompute
  19. 2026-08-02 02:27 UTCEPSS rescore
  20. 2026-08-01 10:30 UTCEG score recompute
  21. 2026-08-01 04:16 UTCEPSS rescore
  22. 2026-07-31 12:00 UTCEG score recompute
  23. 2026-07-30 16:28 UTCEPSS rescore
  24. 2026-07-30 13:30 UTCEG score recompute
  25. 2026-07-30 01:30 UTCEPSS rescore
  26. 2026-07-28 16:31 UTCEG score recompute
  27. 2026-07-28 15:38 UTCEG score recompute
  28. 2026-07-28 15:37 UTCEPSS rescore
  29. 2026-07-27 22:25 UTCEG score recompute
  30. 2026-07-27 08:14 UTCEG score recompute
  31. 2026-07-23 20:12 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-53666?
CVE-2026-53666 is a medium vulnerability published on July 23, 2026. 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…
When was CVE-2026-53666 disclosed?
CVE-2026-53666 was first published in the National Vulnerability Database on July 23, 2026, with the most recent update on August 3, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53666 actively exploited?
CVE-2026-53666 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 77.4% of all scored CVEs.
What is the CVSS score of CVE-2026-53666?
CVE-2026-53666 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-53666?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-53666, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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