CVE-2026-63077 JetBrains TeamCity: unsafe data loading
In plain words: The program unpacks saved data from outside without checking it is safe. Usually lets an attacker run code on the server.
Confirmed exploited by CISA on · US federal patch deadline Aug 8, 2026
What to do
- Install JetBrains's security update for TeamCity. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Keep a list of every internet-facing server you run so nothing is forgotten.
- Patch anything in this catalog first, ahead of normal patch cycles.
- Put admin and file-transfer apps behind a VPN or single sign-on instead of the open internet.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: Mass data theft and ransomware: a single flaw in a file-transfer or email server has exposed thousands of organisations at once.
The details
- Official name
- JetBrains TeamCity Deserialization of Untrusted Data Vulnerability
- Product
- JetBrains TeamCity
- CISA description
- JetBrains TeamCity contains a deserialization of untrusted data vulnerability that could allow unauthenticated remote code execution via the agent polling protocol.
- Type of flaw
- Unsafe data loading (CWE-502)
- Confirmed exploited
- Aug 5, 2026 — known to be used in ransomware attacks
- US federal patch deadline
- Aug 8, 2026
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Answering about CVE-2026-63077 ·
Questions about CVE-2026-63077
Is CVE-2026-63077 being exploited?
Yes. CISA added CVE-2026-63077 to its Known Exploited Vulnerabilities catalog on Aug 5, 2026, which means there is reliable evidence of real-world attacks, including by ransomware groups.
How do I fix CVE-2026-63077?
Install JetBrains's security update for TeamCity. If no update exists, follow the vendor's workaround or stop using the product until one ships. Keep a list of every internet-facing server you run so nothing is forgotten.
Am I affected by CVE-2026-63077?
Only if you use JetBrains TeamCity. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.