---
id: CVE-2025-12799
title: A flaw was found in Jastow
summary: >-
  A flaw was found in Jastow. Jastow is vulnerable to Cross-Site Scripting (XSS)
  attack. If using a set of combined configuration to allow unescaped characters
  in URL with embedded Undertow and Jastow, a server might be vulnerable to
  impro…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N'
cwe:
  - CWE-79
published: '2026-07-07'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T19:10:00.160'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-12799'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:36342'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:36343'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:36344'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:36345'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2025-12799'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2413071'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00408
epssPercentile: 0.32484
ingestedAt: '2026-09-29T19:44:04.102Z'
---

## Overview

A flaw was found in Jastow. Jastow is vulnerable to Cross-Site Scripting (XSS) attack. If using a set of combined configuration to allow unescaped characters in URL with embedded Undertow and Jastow, a server might be vulnerable to improper input handling.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.