CVE-2026-84367
joi: object().rename() with a template target can set the validated object's prototype
Description
joi is a schema description language and data validator for JavaScript. From 16.0.0 until 17.13.5 and 18.2.4, joi's lib/types/keys.js internals.rename() implementation used by object().rename() permits a schema that renames keys with a regular-expression source and a Joi.expression() or Joi.x() target that interpolates the pattern's own match data, combined with { multiple: true }, to derive a target from an attacker-controlled input key. An attacker can send x-__proto__ with an object value, causing the target to render as __proto__ and set the prototype of the object returned by validate() instead of creating an own key. The global Object.prototype is not modified, so the effect is confined to the object returned by that validation call. Static-string targets and schemas using the default { multiple: false } are not affected. This issue is fixed in versions 17.13.5 and 18.2.4.
INFO
Published Date :
Sept. 1, 2026, 9:18 p.m.
Last Modified :
Sept. 1, 2026, 9:18 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-84367
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | LOW | [email protected] |
Solution
- Update joi to version 17.13.5 or later.
- Update joi to version 18.2.4 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-84367.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-84367 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-84367
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-84367 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-84367 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Sep. 01, 2026
Action Type Old Value New Value Added Description joi is a schema description language and data validator for JavaScript. From 16.0.0 until 17.13.5 and 18.2.4, joi's lib/types/keys.js internals.rename() implementation used by object().rename() permits a schema that renames keys with a regular-expression source and a Joi.expression() or Joi.x() target that interpolates the pattern's own match data, combined with { multiple: true }, to derive a target from an attacker-controlled input key. An attacker can send x-__proto__ with an object value, causing the target to render as __proto__ and set the prototype of the object returned by validate() instead of creating an own key. The global Object.prototype is not modified, so the effect is confined to the object returned by that validation call. Static-string targets and schemas using the default { multiple: false } are not affected. This issue is fixed in versions 17.13.5 and 18.2.4. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Added CWE CWE-1321 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/84xxx/CVE-2026-84367.json">CVE-2026-84367</a> Added Reference https://github.com/hapijs/joi/commit/162f367aa178d2e1ebec8dc1164e5fe16536ddf6 Added Reference https://github.com/hapijs/joi/commit/172ececa192feda532b743d77bc9d3e523d19b01 Added Reference https://github.com/hapijs/joi/pull/3134 Added Reference https://github.com/hapijs/joi/pull/3135 Added Reference https://github.com/hapijs/joi/security/advisories/GHSA-gg4h-3hg2-grpc