# CVE-2026-63077: JetBrains TeamCity Deserialization of Untrusted Data

> Unauthenticated attackers can achieve remote code execution on JetBrains TeamCity servers via the agent polling protocol.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 5 Aug 2026 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Jul 2026
- **Updated:** 23 Sep 2026
- **Also known as:** GHSA-94gx-v738-fx9w

## What is CVE-2026-63077?

CVE-2026-63077 is a critical unsafe deserialization vulnerability in Jetbrains Teamcity, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In JetBrains TeamCity before 2026.1.3, 2025.11.7 unauthenticated remote code execution was possible via the agent polling protocol

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-63077?

It affects 1 product.


Products: Jetbrains Teamcity.

## How do I fix CVE-2026-63077?

No fix has been published for CVE-2026-63077 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 8 Aug 2026.

## Is CVE-2026-63077 being exploited?

Yes. Attackers have exploited CVE-2026-63077 in the wild since at least 5 Aug 2026, including in ransomware campaigns.

Public exploit code:

- Unauthenticated Remote Code Execution in JetBrains TeamCity (CVE-2026-63077) (github_poc): https://github.com/sfewer-r7/CVE-2026-63077
- JetBrains TeamCity Agent Polling Unauthenticated Remote Code Execution (metasploit)
- JetBrains TeamCity On-Premises CVE-2026-63077 Emergency Hardening & Patch Runbook Package (github_poc): https://github.com/unveiledhistory49/teamcity-cve-2026-63077-remediation
- teamcity teamcity-CVE-2026-63077 exploitation pcap (github_poc): https://github.com/BoredHackerBlog/teamcity-CVE-2026-63077-pcap
- CVE-2026-63077 — Unauthenticated Remote Code Execution in JetBrains TeamCity via agent polling protocol deserialization. CVSS 9.8 CRITICAL. Mass exploitation tool with interactive shell, multi-threading, and real-time result logging. (github_poc): https://github.com/AnggaTechI/CVE-2026-63077
- JetBrains TeamCity On-Premises CVE-2026-63077 Emergency Hardening & Patch Runbook Package (github_poc): https://github.com/bakos-sandor-nx/teamcity-cve-2026-63077-remediation

## Other vulnerabilities in Jetbrains Teamcity

- [CVE-2024-27198](https://insights.sbomify.com/CVE-2024-27198/): JetBrains TeamCity Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2023-42793](https://insights.sbomify.com/CVE-2023-42793/): JetBrains TeamCity Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2024-27199](https://insights.sbomify.com/CVE-2024-27199/): JetBrains TeamCity Relative Path Traversal (high 7.3, exploited in the wild)
- [CVE-2024-23917](https://insights.sbomify.com/CVE-2024-23917/): Auth bypass in TeamCity (critical 9.8)
- [CVE-2022-24331](https://insights.sbomify.com/CVE-2022-24331/): Auth bypass in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63077 and fix it if it is affected.

What it is: CVE-2026-63077 is a critical unsafe deserialization vulnerability in Jetbrains Teamcity, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2026-63077 in the wild since at least 5 Aug 2026, including in ransomware campaigns.

Affected product: Jetbrains Teamcity. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63077/ (Markdown: https://insights.sbomify.com/CVE-2026-63077/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63077
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63077
- OSV: https://osv.dev/vulnerability/CVE-2026-63077

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63077/
Summaries are generated and may contain mistakes; the official description above is the record.