---
id: CVE-2026-100263
title: >-
  In JetBrains YouTrack before 2026.2.18991 stored HTML injection via the
  User-Agent header was possible
summary: >-
  In JetBrains YouTrack before 2026.2.18991 stored HTML injection via the
  User-Agent header was possible
severity: medium
cvss: 4.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N'
cwe:
  - CWE-79
vendor: jetbrains
product: youtrack
affected:
  - youtrack < 2026.2.18991
patched:
  - youtrack 2026.2.18991
published: '2026-09-30'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T20:23:31.353'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100263'
references:
  - url: 'https://www.jetbrains.com/privacy-security/issues-fixed/'
    label: cve@jetbrains.com
tags:
  - nvd
  - cve.org
epss: 0.00192
epssPercentile: 0.08812
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-30T15:35:06.223894Z'
ingestedAt: '2026-09-30T16:10:07.681Z'
---

## Overview

In JetBrains YouTrack before 2026.2.18991 stored HTML injection via the User-Agent header was possible

## Affected

- `youtrack < 2026.2.18991`

## Remediation

Upgrade past the affected range:

- `youtrack 2026.2.18991`