CVE-2026-31865

Name: CVE-2026-31865
Creator: NVD / NIST
Published: 2026-03-18T04:17:19.393+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.23%

Last modified Jun 17, 2026

CVE-2026-31865 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. EPSS estimates a 0.23% chance of exploitation in the next 30 days.

Description

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. `__proto__`. This issue is patched in 1.4.27. As a workaround, use t.Cookie validation to enforce validation value and/or prevent iterable over cookie if possible.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability

0.23%

14.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-1321

Affected Software

Vendor	Product	Versions
Elysiajs	Elysia	< 1.4.27

References

https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aabPatch
https://github.com/elysiajs/elysia/security/advisories/GHSA-8hq9-phh3-p2wpMitigation, Patch, Vendor Advisory

Timeline

Published: Mar 18, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-31865?

How severe is CVE-2026-31865?

CVE-2026-31865 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.

How do I fix CVE-2026-31865?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-31865?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST