PatchSiren cyber security CVE debrief

CVE-2026-49375 JetBrains CVE debrief

A reflected cross-site scripting (XSS) vulnerability exists in JetBrains TeamCity versions prior to 2026.1 and 2025.11.5. The flaw affects the repository download page and could allow an attacker to execute malicious scripts in a victim's browser context. The CVSS 3.1 score of 6.1 (MEDIUM) reflects network attack vector, low attack complexity, no privileges required, but user interaction required, with scope change and low impacts to confidentiality and integrity. The vulnerability was published to the CVE database on May 29, 2026, and is currently undergoing analysis by NVD. JetBrains has addressed this issue in the specified fixed versions.

Vendor: JetBrains
Product: TeamCity
CVSS: MEDIUM 6.1
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-05-29
Original CVE updated: 2026-05-29
Advisory published: 2026-05-29
Advisory updated: 2026-05-29

Who should care

Organizations running JetBrains TeamCity CI/CD servers, particularly those with externally accessible repository download pages. Security teams responsible for application security and developers using TeamCity for build automation.

Technical summary

Reflected XSS vulnerability in JetBrains TeamCity before 2026.1 and 2025.11.5 on the repository download page. CVSS 3.1 score 6.1 (MEDIUM). Fixed versions available.

Defensive priority

medium

Recommended defensive actions

Upgrade JetBrains TeamCity to version 2026.1 or 2025.11.5 or later
Review access logs for suspicious requests to the repository download page containing script tags or encoded JavaScript payloads
Implement Content Security Policy (CSP) headers as a defense-in-depth measure
Validate and sanitize all user-supplied input reflected in web page responses
Consider web application firewall (WAF) rules to detect and block XSS attempts

Evidence notes

The vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation). The affected product is confirmed as JetBrains TeamCity based on the CVE description and vendor reference. The fix versions are explicitly stated as 2026.1 and 2025.11.5.

Official resources

JetBrains disclosed this vulnerability through their security issues fixed page. The CVE was assigned and published to NVD on May 29, 2026.