JetBrains TeamCity CVE-2026-49377

Exploitation requires a valid TeamCity account with at minimum low-level privileges sufficient to view default agent parameters - confirmed by CVSS PR:L. The vulnerability is triggered by the presence of sensitive data (e.g., credentials, tokens) stored in default build agent parameters, which is a common but not universal configuration pattern. Exploitation is limited by: (1) authenticated access requirement - unauthenticated users cannot exploit this; (2) the vulnerability only has impact if sensitive values are actually present in agent parameters - environments that store no secrets there are not at material risk; (3) no user interaction is required (UI:N), meaning an attacker does not need to trick another user. No special protocol, non-default service, or rare deployment mode is required beyond standard TeamCity agent configuration.

The CVSS score of 4.3 (Medium) reflects a constrained but real-world risk. The attack vector is network-based (AV:N) with low complexity (AC:L), meaning no special conditions are needed to reach the vulnerable component once authentication is achieved. PR:L confirms exploitation requires a valid low-privileged TeamCity account, which limits the exposed attack surface to insider threats, compromised user accounts, or environments with open self-registration. The confidentiality impact is rated Low (C:L), suggesting partial or indirect access to sensitive data rather than full credential dump. No public exploit code has been identified at time of analysis, and this CVE is not listed in the CISA KEV catalog. EPSS data is not provided, but given the authenticated requirement and low C impact, real-world exploitation probability is likely modest. The primary real-world risk is privilege escalation: a low-privileged developer reading agent parameters containing service account tokens or deployment secrets could pivot to higher-access systems. Defenders should weigh whether their TeamCity agent parameters currently store sensitive values.

An authenticated low-privileged TeamCity user - such as a developer with project-level access - navigates to the build agent configuration or parameter settings page and observes default agent parameters that expose sensitive values such as deployment tokens or internal API keys in cleartext. No public exploit code exists for this issue, but the steps are trivially reproducible by any valid user with sufficient UI access. The extracted credentials could then be used to authenticate to downstream systems integrated with the CI/CD pipeline.