JetBrains is urging Cadence users to revoke and rotate all credentials following a security incident last month in which unidentified threat actors exploited a recently disclosed critical vulnerability in TeamCity to breach its own environment. "Cadence users should immediately revoke or rotate all credentials and secrets that may have been used to run their Cadence executions," JetBrains said. "They should also treat all executions, including their inputs and outputs in your Cadence project, as potentially untrusted." "As the threat actors gained access to the Cadence server, any credentials or secrets stored in Cadence, contained in the compromised backup, or made available to executions on the affected server should be considered compromised and must be revoked or rotated." Cadence is a JetBrains-hosted cloud computing service that integrates with PyCharm via an optional plugin to let developers run machine learning and heavy workloads on cloud GPUs directly from their IDE. The attack, per the software development company, involved the exploitation of CVE-2026-63077 (CVSS score: 9.8) to breach the affected Cadence environments. The deserialization of untrusted data vulnerability can permit an unauthenticated attacker with access to a TeamCity server to bypass authentication checks and execute arbitrary operating system commands with the privileges of the TeamCity server process. The security flaw has since come under active exploitation in the wild, with the U.S. Cybersecurity and Infrastructure Security Agency (CISA) adding it to the Known Exploited Vulnerabilities (KEV) catalog on August 5, 2026. The exploitation was discovered by JetBrains on August 23, 2026. In subsequent updates, JetBrains said the threat actor accessed data contained in the Cadence server backup from 2024 and that they obtained unauthorized access that could have allowed them to reach storage containing data associated with current Cadence users, including email addresses, project source code, and credentials. "This affects the same group