CVE-2026-66296
Reflected XSS in oaskit's default HTML error handler
Description
Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler. Oaskit.ErrorHandler.Default.format_reason/4 and Oaskit.ErrorHandler.Default.reason_to_html/1 in lib/oaskit/error_handler/default.ex render request-validation failures as an HTML page whenever the request's Accept header contains html, interpolating request-controlled strings into that page without HTML escaping. The unescaped values are object keys taken from a request body or from an object or deepObject query parameter, which appear in the JSON Schema error's instance path when a schema rejects them (for example under additionalProperties: false), and the raw Content-Type header, reflected in unsupported-media-type errors when it fails to parse. Because browsers send Accept: text/html on ordinary top-level navigation, a crafted GET link is sufficient to trigger the error page; no form submission, custom Content-Type, or attacker-controlled script on the victim's side is required. A payload such as filter[</code></h2><script>alert(document.domain)</script>]=x terminates the enclosing markup and the injected script executes in the origin of the application using oaskit, giving it access to that origin's cookies, session, and same-origin responses. Both HTML error rendering and the vulnerable handler are enabled by default: Oaskit.Plugs.ValidateRequest defaults :html_errors to true and :error_handler to Oaskit.ErrorHandler.Default, so applications following the documented usage are affected without any opt-in. This issue affects oaskit: from 0.1.0 before 0.14.1.
INFO
Published Date :
Aug. 3, 2026, 8:17 p.m.
Last Modified :
Oct. 23, 2026, 9:10 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update Oaskit to a version that includes the fix.
- Ensure HTML escaping is enabled for user-controlled input.
- Review and sanitize all user-supplied data.
- Configure error handling to prevent script injection.
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-2026-66296.
| URL | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-66296.html | Patch Third Party Advisory |
| https://github.com/lud/oaskit/commit/b70c6b2eaf0b11bdd0bbb21b8a87dbb3d46918a1 | Patch |
| https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc | Exploit Vendor Advisory |
| https://osv.dev/vulnerability/EEF-CVE-2026-66296 | Patch Third Party Advisory |
| https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-66296 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-2026-66296
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-2026-66296 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-66296 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.
-
CVE Translated by [email protected]
Oct. 23, 2026
Action Type Old Value New Value Added Translation Title: oaskit de lud, Description: Vulnerabilidad de Neutralización Incorrecta de Entrada Durante la Generación de Páginas Web (XSS) en lud oaskit permite cross-site scripting reflejado a través del gestor de errores HTML predeterminado. Oaskit.ErrorHandler.Default.format_reason/4 y Oaskit.ErrorHandler.Default.reason_to_html/1 en lib/oaskit/error_handler/default.ex renderizan fallos de validación de solicitudes como una página HTML siempre que el encabezado Accept de la solicitud contenga html, interpolando cadenas controladas por la solicitud en esa página sin escape HTML. Los valores sin escape son claves de objeto tomadas de un cuerpo de solicitud o de un parámetro de consulta de tipo object o deepObject, que aparecen en la ruta de instancia del error de JSON Schema cuando un esquema los rechaza (por ejemplo, bajo additionalProperties: false), y el encabezado Content-Type sin procesar, reflejado en errores de tipo de medio no compatible (unsupported-media-type) cuando falla al analizarse. Debido a que los navegadores envían Accept: text/html en la navegación de nivel superior ordinaria, un enlace GET manipulado es suficiente para activar la página de error; no se requiere el envío de formularios, un Content-Type personalizado o un script controlado por el atacante en el lado de la víctima. Una carga útil como filter[[/code][/h2][script_tag]alert(document.domain)[/script]]=x termina el marcado envolvente y el script inyectado se ejecuta en el origen de la aplicación que utiliza oaskit, dándole acceso a las cookies, la sesión y las respuestas del mismo origen de ese origen. Tanto la renderización de errores HTML como el gestor vulnerable están habilitados por defecto: Oaskit.Plugs.ValidateRequest establece por defecto :html_errors en true y :error_handler en Oaskit.ErrorHandler.Default, por lo que las aplicaciones que siguen el uso documentado se ven afectadas sin necesidad de una activación explícita. Este problema afecta a oaskit: desde 0.1.0 antes de 0.14.1. -
Initial Analysis by [email protected]
Aug. 17, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:lud:oaskit:*:*:*:*:*:*:*:* versions from (including) 0.1.0 up to (excluding) 0.14.1 Added Reference Type CISA-ADP: https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc Types: Exploit, Vendor Advisory Added Reference Type EEF: https://cna.erlef.org/cves/CVE-2026-66296.html Types: Patch, Third Party Advisory Added Reference Type EEF: https://github.com/lud/oaskit/commit/b70c6b2eaf0b11bdd0bbb21b8a87dbb3d46918a1 Types: Patch Added Reference Type EEF: https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc Types: Exploit, Vendor Advisory Added Reference Type EEF: https://osv.dev/vulnerability/EEF-CVE-2026-66296 Types: Patch, Third Party Advisory -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Aug. 03, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:lud:oaskit:*:*:*:*:*:elixir:*:*'], 'repo': 'https://github.com/lud/oaskit', 'vendor': 'lud', 'modules': ['Elixir.Oaskit.ErrorHandler.Default'], 'product': 'oaskit', 'versions': [{'status': 'affected', 'version': '0.1.0', 'lessThan': '0.14.1', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/oaskit', 'packageName': 'oaskit', 'programFiles': ['lib/oaskit/error_handler/default.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.Oaskit.ErrorHandler.Default':format_reason/4"}, {'name': "'Elixir.Oaskit.ErrorHandler.Default':reason_to_html/1"}]}, {'cpes': ['cpe:2.3:a:lud:oaskit:*:*:*:*:*:elixir:*:*'], 'repo': 'https://github.com/lud/oaskit', 'vendor': 'lud', 'modules': ['Elixir.Oaskit.ErrorHandler.Default'], 'product': 'oaskit', 'versions': [{'status': 'affected', 'version': '552de8ca0ff60617bea58bcafa451892d61a161c', 'lessThan': 'b70c6b2eaf0b11bdd0bbb21b8a87dbb3d46918a1', 'versionType': 'git'}], 'packageURL': 'pkg:github/lud/oaskit', 'packageName': 'lud/oaskit', 'programFiles': ['lib/oaskit/error_handler/default.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.Oaskit.ErrorHandler.Default':format_reason/4"}, {'name': "'Elixir.Oaskit.ErrorHandler.Default':reason_to_html/1"}]}] Added Description Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler. Oaskit.ErrorHandler.Default.format_reason/4 and Oaskit.ErrorHandler.Default.reason_to_html/1 in lib/oaskit/error_handler/default.ex render request-validation failures as an HTML page whenever the request's Accept header contains html, interpolating request-controlled strings into that page without HTML escaping. The unescaped values are object keys taken from a request body or from an object or deepObject query parameter, which appear in the JSON Schema error's instance path when a schema rejects them (for example under additionalProperties: false), and the raw Content-Type header, reflected in unsupported-media-type errors when it fails to parse. Because browsers send Accept: text/html on ordinary top-level navigation, a crafted GET link is sufficient to trigger the error page; no form submission, custom Content-Type, or attacker-controlled script on the victim's side is required. A payload such as filter[</code></h2><script>alert(document.domain)</script>]=x terminates the enclosing markup and the injected script executes in the origin of the application using oaskit, giving it access to that origin's cookies, session, and same-origin responses. Both HTML error rendering and the vulnerable handler are enabled by default: Oaskit.Plugs.ValidateRequest defaults :html_errors to true and :error_handler to Oaskit.ErrorHandler.Default, so applications following the documented usage are affected without any opt-in. This issue affects oaskit: from 0.1.0 before 0.14.1. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-79 Added Reference https://cna.erlef.org/cves/CVE-2026-66296.html Added Reference https://github.com/lud/oaskit/commit/b70c6b2eaf0b11bdd0bbb21b8a87dbb3d46918a1 Added Reference https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-66296 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 03, 2026
Action Type Old Value New Value Added Reference https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc Added SSVC {'id': 'CVE-2026-66296', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-03T19:50:03.665445Z'}