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CVE-2026-53666VulnerabilityPublished

CVE-2026-53666: remix-run react-router · Unsafe Reflection

Affects remix-run react-routerSource CVE Database V5

0

Not known to be exploited · CVSS 6.1 Medium : upgrade to 7.18.0 when convenient.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score
6.1Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 7.18.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade remix-run react-router to 7.18.0.

Affected software

ProductAffectedFixed in
remix-runreact-routerAffected
  • >=6.4.0 <7.18.0
Fixed in
  • 7.18.0

AI-suggested

Upgrade react-router to version 7.18.0 or later, where this vulnerability is fixed. If upgrading is not immediately possible, avoid using Framework Mode or Data Mode with manual SSR/hydration in a way that allows attacker-controlled input to overwrite error aspects. Applications using Declarative Mode are not affected and require no action.

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.

References

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