Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2026-63077

TeamCity Remote Code Execution

JetBrains / TeamCity · affected before 2026.1.3, 2025.11.7

Watch CVE-2026-63077 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
89.6%
First observed
27 Sep 2026
Last observed
07 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-63077 is an unauthenticated vulnerability affecting JetBrains TeamCity. In JetBrains TeamCity before 2026.1.3, 2025.11.7 unauthenticated remote code execution was possible via the agent polling protocol

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

JetBrains / TeamCity affected before 2026.1.3, 2025.11.7.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

TeamCity Remote Code Execution

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

JetBrains Affected
TeamCity
Before 2026.1.3, 2025.11.7
Published
27 Jul 2026
Exploitation Reported
05 Aug 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa nuclei_scanner

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 05 Aug 2026

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 27 Sep 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

GitHub

Recorded 08 Aug 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2026-08-05 16:50 UTC
CVE 2026-08-05 18:01 UTC
The Hacker News 2026-08-06 06:51 UTC
Rapid7 2026-08-07 14:32 UTC
Previdian Sensors 2026-09-27 20:46 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

7

Attempts observed

2

Unique attacker IPs

2

Attacker countries

NL · PK

1

Sensors observed

CVE-2026-63077 exploitation attempts over the last 23 days

Daily events observed by Previdian sensors

Updated 18 Oct 2026

0
3
0
0
0
0
0
0
0
0
0
4
0
0
0
0
0
0
0
0
0
0
0
26 Sep 1 Oct 6 Oct 11 Oct 18 Oct

First observed 27 Sep 2026 · Last observed 07 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
2
3
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-63077.yaml 10 Aug 2026

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

89.6%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Deserialization of Untrusted Data CWE-502

Recent mention · Rapid7

Metasploit Wrap Up: This One Goes to Sixteen!

This One Goes to Sixteen!Another banger from Metasploit with sixteen new modules, including ten exploit modules, with five on the CISA KEV list. Cisco, Papercut, Sonicwall, Jetbrains, and Langflow all have exploit modules, and not to be outdone, we even have a Metasploit...

Read full advisory

All Mentions

Recent mention · Rapid7

Metasploit Wrap Up: This One Goes to Sixteen!

Rapid7 · 11 Sep 2026

This One Goes to Sixteen!Another banger from Metasploit with sixteen new modules, including ten exploit modules, with five on the CISA KEV list. Cisco, Papercut, Sonicwall, Jetbrains, and Langflow all have exploit modules, and not to be outdone, we even have a Metasploit scanner to watch the watchers!New module content (16)Elasticsearch ingest-attachment Apache Tika XFA XXE Local File ReadAuthors: Bourbon Offensive Security Services and Jean-Marie BourbonType: AuxiliaryPull request: #21739 contributed by kmkzPath: scanner/http/elasticsearch_tika_xfa_xxeCVE...

Recent mention · RecordedFuture

August 2026 CVE Landscape

RecordedFuture · 08 Sep 2026

In August 2026, Insikt Group® identified 73 high-impact vulnerabilities that should be prioritized for remediation, 43 of which had a Very Critical Recorded Future Risk Score. This represents a 14% decrease from last month.

Recent mention · Rapid7

Rapid7 Analysis: Unauthenticated Remote Code Execution in JetBrains TeamCity (CVE-2026-63077)

Rapid7 · 07 Aug 2026

OverviewOn July 27, 2026, JetBrains published a security advisory for CVE-2026-63077, a critical unsafe deserialization vulnerability affecting JetBrains TeamCity. An attacker who can reach a TeamCity server over HTTP or HTTPS can exploit the agent polling protocol without credentials and execute operating system commands with the privileges of the TeamCity server process.JetBrains reported no known active exploitation when it disclosed the vulnerability. However, on August 5, 2026, CISA added CVE-2026-63077 to its Known Exploited Vulnerabilities (KEV) catalog, confirming exploitation in...

Recent mention · The Hacker News

CISA Flags TeamCity CVE-2026-63077 RCE Flaw Under Active Exploitation in the Wild

The Hacker News · 06 Aug 2026

A newly patched security flaw impacting on-premise versions of JetBrains TeamCity has come under active exploitation in the wild, according to the U.S. Cybersecurity and Infrastructure Security Agency (CISA). The vulnerability in question is CVE-2026-63077 (CVSS score: 9.8), a case of deserialization of untrusted data that could allow an unauthenticated attacker with access to a TeamCity server

Recent mention · Rapid7

CVE-2026-63077: Critical unauthenticated remote code execution in JetBrains TeamCity

Rapid7 · 29 Jul 2026

OverviewOn July 27, 2026, JetBrains published a security advisory for CVE-2026-63077, a critical unauthenticated vulnerability affecting all versions of TeamCity On-Premises. The issue is classified as deserialization of untrusted data and has a CVSS score of 9.8. An unauthenticated remote attacker with HTTP(S) access to a TeamCity server can exploit the agent polling protocol to bypass authentication checks and execute arbitrary operating system commands with the privileges of the TeamCity server process.In the blog post that JetBrains shared in tandem with CVE publication, they stated...

Recent mention · The Hacker News

Critical TeamCity Flaw Could Let Attackers Run OS Commands Without Logging In

The Hacker News · 28 Jul 2026

JetBrains is urging customers of on-premise versions of TeamCity to update to the latest version following the discovery of a critical security issue that could result in arbitrary code execution. The vulnerability, assigned CVE-2026-63077 (CVSS score: 9.8), affects all TeamCity On-Premises versions. It has been addressed in versions 2025.11.7 and 2026.1.3. TeamCity Cloud instances have already

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

0xCyp1337/CVE-2026-63077

github · Created 2026-09-04 13:32:31 UTC · 0 stars · AI assessment 90%

CVE-2026-63077 - Unauthenticated RCE exploit for JetBrains TeamCity via Agent Polling Deserialization. Supports mass scanning, multi-threading, and interactive shell. For authorized security testing only.

JetBrains TeamCity On-Premises unauthenticated RCE via agent polling protocol

pruva · Created 2026-08-23 15:38:48 UTC

Severity: CRITICAL | CVE: CVE-2026-63077 | Package: JetBrains TeamCity

AnggaTechI/CVE-2026-63077

github · Created 2026-08-08 06:32:09 UTC · 0 stars · AI assessment 90%

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.

sfewer-r7/CVE-2026-63077

github · Created 2026-08-07 08:38:01 UTC · 1 stars · AI assessment 90%

Unauthenticated Remote Code Execution in JetBrains TeamCity (CVE-2026-63077)

JetBrains TeamCity < 2026.1.3, 2025.11.7 - Remote Code Execution

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 20:44 UTC

    Indicators of compromise added (2)

    Indicators of compromise recorded

  2. 20:44 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  3. 04:30 UTC

    Nuclei template available

    Scanner coverage available

  4. 14:32 UTC

    KEV confirmed by Rapid7

    Exploitation attested by an external source

  5. 08:38 UTC

    Public PoC available

    Public proof-of-concept code published

  6. 06:51 UTC

    KEV confirmed by The Hacker News

    Exploitation attested by an external source

  7. 18:01 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  8. 16:50 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  9. 16:44 UTC

    CVE published

    Vulnerability disclosed publicly

  10. 15:12 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-63077

Sample API response 
{
  "cve_id": "CVE-2026-63077",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.8957,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 7, "sensors": 1 }
}