CVE-2026-63077

JetBrains TeamCity: Deserialization of Untrusted Data

As of , CVE-2026-63077 in JetBrains TeamCity is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch now.

Exploited
Yes: CISA listed it on 5 August 2026
US federal deadline
8 August 20263 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
KnownCISA changed it from Unknown to Known on 23 September 2026.
Forensic triage
Required by CISA under BOD 26-04Agencies must also look for signs that attackers already got in.
EPSS score
0.90Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
1 Metasploit module
Fix
Vendor advice: blog.jetbrains.com and www.jetbrains.comLinks below, from CISA's entry.

What CISA says to do

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

CISA's required action

What the flaw is

JetBrains TeamCity contains a deserialization of untrusted data vulnerability that could allow unauthenticated remote code execution via the agent polling protocol.

CISA's description

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

The CVE record's description, from JetBrains

CVE published
27 July 2026
Assigned by
JetBrains
CVSS
9.8 Critical (CVSS 3.1, from the CNA)
CWE-502
Deserialization of Untrusted Data
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.
  4. CISA changed its entry. Ransomware use: Unknown to Known.

Public exploits

Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.

  • Metasploit: JetBrains TeamCity Agent Polling Unauthenticated Remote Code Executionexploit module, rank excellent

TeamCity: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2024-27199Relative Path TraversalJetBrains TeamCityPatch nowRansomware use, listed within a year0.99
CVE-2024-27198Authentication BypassJetBrains TeamCityPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2023-42793Authentication BypassJetBrains TeamCityPatch this weekRansomware use; Metasploit module; EPSS 0.990.99

Read further