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Vulnerabilities

Vulnerability · CVE-2026-41690

18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno.

Published May 8, 2026 · catalog updated Jun 17, 2026 · 18next-http-middleware is a middleware

Check if you run it

No confirmed exploitation is on record for CVE-2026-41690. EPSS is 0.47%. Act only if a listed version of 18next-http-middleware is a middleware is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (18next-http-middleware is a middleware).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.6
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.47%
Remediation
Advisory link
Affected products
See sources for product scope

18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Versions prior to 3.9.3 allow an unauthenticated HTTP client to pollute Object.prototype in the Node.js process hosting the middleware, via two unvalidated entry points that reach internal object-key writes: getResourcesHandler and missingKeyHandler. This can break authorisation checks (if (user.isAdmin) returning true for any user), cause type-confusion DoS, and depending on downstream code it can be chained into RCE.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-41690

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-41690. EPSS is 0.47%. Act only if a listed version of 18next-http-middleware is a middleware is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1321: Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution); CWE-22: Path Traversal. EPSS 0.47%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 8, 2026 · NIST NVD

    Detected

    18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Versions prior to 3.9.3 allow an unauthenticated HTTP client to pollute Object.prototype in the Node.js process hosting the middleware, via two unvalidated entry points that reach internal object-key writes: getResourcesHandler and missingKeyHandler. This can break authorisation

  2. Jun 17, 2026 · NIST NVD

    Updated

    18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Versions prior to 3.9.3 allow an unauthenticated HTTP client to pollute Object.prototype in the Node.js process hosting the middleware, via two unvalidated entry points that reach internal object-key writes: getResourcesHandler and missingKeyHandler. This can break authorisation

Sources

  • CVE.orgVulnerability recordCVE-2026-41690

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-41690

    30-day exploitation probability 0.5%

    first.org
  • NIST NVDVulnerability recordCVE-2026-41690

    18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Versions prior to 3.9.3 allow an unauthenticated HTTP client to pollute Object.prototype in the Node.js process hosting the middleware, via two unvalidated ent

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.