CVE-2026-100263: CWE-79 in JetBrains YouTrack
CVE-2026-100263 is a stored HTML injection vulnerability in JetBrains YouTrack versions before 2026.2.18991. The vulnerability arises from improper handling of the User-Agent header, allowing malicious HTML content to be stored. This issue has a medium severity rating with a CVSS score of 4.7. No known exploits are reported in the wild. The vulnerability affects YouTrack versions from initial releases up to but not including 2026.2.18991.
AI Analysis
Technical Summary
JetBrains YouTrack before version 2026.2.18991 is affected by a stored HTML injection vulnerability (CWE-79) via the User-Agent HTTP header. This flaw allows an attacker to inject HTML content that is stored and potentially rendered later, which can lead to partial confidentiality impact. The CVSS 3.1 score is 4.7, indicating medium severity with network attack vector, low attack complexity, no privileges required, user interaction required, and scope changed. There is no indication of integrity or availability impact. No exploits are known in the wild at this time.
Potential Impact
An attacker can inject stored HTML content through the User-Agent header, potentially leading to partial confidentiality loss when the injected content is viewed. There is no reported impact on integrity or availability. The vulnerability requires user interaction and can be exploited remotely without authentication.
Mitigation Recommendations
A fix is available in JetBrains YouTrack version 2026.2.18991. Users should upgrade to this version or later to remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-100263: CWE-79 in JetBrains YouTrack
Description
CVE-2026-100263 is a stored HTML injection vulnerability in JetBrains YouTrack versions before 2026.2.18991. The vulnerability arises from improper handling of the User-Agent header, allowing malicious HTML content to be stored. This issue has a medium severity rating with a CVSS score of 4.7. No known exploits are reported in the wild. The vulnerability affects YouTrack versions from initial releases up to but not including 2026.2.18991.
CVSS v3.1
Score 4.7medium
Affected software
JetBrains
YouTrack
pkg:github/jetbrains/YouTrackRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
JetBrains YouTrack before version 2026.2.18991 is affected by a stored HTML injection vulnerability (CWE-79) via the User-Agent HTTP header. This flaw allows an attacker to inject HTML content that is stored and potentially rendered later, which can lead to partial confidentiality impact. The CVSS 3.1 score is 4.7, indicating medium severity with network attack vector, low attack complexity, no privileges required, user interaction required, and scope changed. There is no indication of integrity or availability impact. No exploits are known in the wild at this time.
Potential Impact
An attacker can inject stored HTML content through the User-Agent header, potentially leading to partial confidentiality loss when the injected content is viewed. There is no reported impact on integrity or availability. The vulnerability requires user interaction and can be exploited remotely without authentication.
Mitigation Recommendations
A fix is available in JetBrains YouTrack version 2026.2.18991. Users should upgrade to this version or later to remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- JetBrains
- Date Reserved
- 2026-09-25T17:02:05.789Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6abd2c322a4e24523d2ec304
Added to database: 09/30/2026, 15:35:14 UTC
Last enriched: 09/30/2026, 15:51:18 UTC
Last updated: 10/01/2026, 03:42:33 UTC
Views: 11
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