# CVE-2026-49376: JetBrains TeamCity insufficient username validation in SAML plugin

Source: https://junglewise.ai/threats/cve-2026-49376-jetbrains-teamcity-insufficient-username-validation-in-saml  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-29. Updated: 2026-05-29  
License: CC BY 4.0 with a link back

CVE-2026-49376 · Severity: medium · CVSS 6.5 · Published 2026-05-29

JetBrains TeamCity, a platform used by software teams to automate building and testing code, contains a security flaw in its SAML authentication plugin. This vulnerability allows for insufficient validation of usernames during the login process. If exploited, it could potentially allow unauthorized individuals to gain limited access to the system or manipulate user identity data, impacting the integrity of the development environment.

Technologies: [Jetbrains TeamCity](https://junglewise.ai/threats/technologies/teamcity). Vendors: [Jetbrains](https://junglewise.ai/threats/vendors/jetbrains).

## Quick answers

**Is CVE-2026-49376 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-49376 being exploited in the wild.

**How severe is CVE-2026-49376?** Medium severity, with a CVSS score of 6.5, published 29 May 2026.

**Which products and versions are affected?** Jetbrains TeamCity before 2026.1.

**Is there a fix for CVE-2026-49376?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-49376 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-49376?** Check whether you run Jetbrains TeamCity at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An incorrect authorization vulnerability (CWE-863) exists in the JetBrains TeamCity SAML plugin for versions prior to 2026.1. The root cause is insufficient validation of usernames provided during the SAML authentication flow. A remote, unauthenticated attacker can exploit this over the network without user interaction. Successful exploitation could lead to unauthorized access or data modification (Low impact to Confidentiality and Integrity). The issue is addressed in TeamCity version 2026.1.

## Affected products

- JetBrains TeamCity before 2026.1

## Timeline

- 2026-05-29: disclosed
- 2026-05-29: advisory

## References

- [https://www.jetbrains.com/privacy-security/issues-fixed/](https://www.jetbrains.com/privacy-security/issues-fixed/)

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