VDB-412156 · CVE-2026-100263 · GCVE-0-2026-100263

JetBrains YouTrack up to 2026.2.18990 User-Agent cross site scripting

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.4	$0-$5k	0.00

Summaryinfo

A vulnerability labeled as problematic has been found in JetBrains YouTrack up to 2026.2.18990. This affects an unknown function. Executing a manipulation of the argument User-Agent can lead to cross site scripting. This vulnerability is handled as CVE-2026-100263. The attack can be executed remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic was found in JetBrains YouTrack up to 2026.2.18990. This vulnerability affects an unknown part. The manipulation of the argument User-Agent with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. CVE summarizes:

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

The advisory is shared for download at jetbrains.com. This vulnerability was named CVE-2026-100263 since 09/25/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Upgrading to version 2026.2.18991 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Bug Tracking Software

Vendor

JetBrains

Name

YouTrack

Version

2026.2.18990

License

free

CPE 2.3info

🔒

CPE 2.2info

🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.5
VulDB Meta Temp Score: 4.4

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.7
CNA Vector (JetBrains): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: YouTrack 2026.2.18991

Timelineinfo

09/25/2026 CVE reserved
09/30/2026 +5 days Advisory disclosed
09/30/2026 +0 days VulDB entry created
09/30/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: jetbrains.com
Status: Confirmed

CVE: CVE-2026-100263 (🔒)
GCVE (CVE): GCVE-0-2026-100263
GCVE (VulDB): GCVE-100-412156

Entryinfo

Created: 09/30/2026 17:50
Changes: 09/30/2026 17:50 (64)
Complete: 🔍
Cache ID: 216::103