SB2026100226 - Multiple vulnerabilities in TeamCity
Published: October 2, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 vulnerabilities.
1) Improper Validation of Unsafe Equivalence in Input (CVE-ID: CVE-2026-100255)
CWE-ID: CWE-1289 - Improper Validation of Unsafe Equivalence in Input
CVSSv4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to take over an administrator account.
The vulnerability exists due to improper validation of unsafe equivalence in input in the password reset process when processing password reset requests. A remote attacker can reset an administrator account password to take over an administrator account.
2) OS Command Injection (CVE-ID: CVE-2026-100254)
CWE-ID: CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to execute commands on Windows servers.
The vulnerability exists due to improper neutralization of CRLF sequences in Pipeline Git connection settings when configuring connection settings with CRLF sequences. A remote user can inject CRLF sequences into Pipeline Git connection settings to execute commands on Windows servers.
3) Incomplete List of Disallowed Inputs (CVE-ID: CVE-2026-100253)
CWE-ID: CWE-184 - Incomplete List of Disallowed Inputs
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to execute arbitrary code.
The vulnerability exists due to incomplete blacklist validation in the versioned settings Kotlin DSL sandbox when processing versioned settings Kotlin DSL code. A remote user can provide crafted Kotlin DSL code to escape the sandbox and execute arbitrary code.
Remediation
Install update from vendor's website.