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

Q: How do I fix CVE-2026-63077?

teamcity: upgrade to 2025.11.7, 2026.1.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-63077 being exploited?

Yes. CVE-2026-63077 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2026-63077 affect?

CVE-2026-63077 affects teamcity. Severity is critical (CVSS 9.8). In JetBrains TeamCity before 2026.1.3, 2025.11.7 unauthenticated remote code execution was possible via the agent polling protocol

Q: How urgent is CVE-2026-63077?

Priority 100/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Used in ransomware campaigns; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

100

Patch now

CRITICAL 9.8EXPLOITEDREMOTEUPGRADE

CVE-2026-63077 is a critical-severity flaw (CVSS 9.8) affecting teamcity, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
Used in ransomware campaigns
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	89.6% (top 1%)
CISA exploited list	Yes, fix due 2026-08-08, used in ransomware
Weakness	CWE-502
Published	2026-07-27
Last modified	2026-10-24

Publisher (CNA): JetBrains s.r.o. · Vendor: jetbrains

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-27 17:16 UTCPublished CVE record published
2026-08-05Exploited Added to the CISA Known Exploited Vulnerabilities list
2026-08-08Deadline CISA due date for US federal agencies to patch
2026-10-24 13:10 UTCUpdated Record last modified

jetbrains teamcity UPGRADE

Affected: < 2025.11.7 · >= 2026.1 and < 2026.1.3

Fixed in: 2025.11.7, 2026.1.3

Safe to downgrade to: a release before 2026.1

1. Check installed version

apt-cache policy teamcity || rpm -q teamcity || teamcity --version

2. UPGRADE to 2025.11.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade teamcity

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade teamcity

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2026.1 (Debian / Ubuntu)

apt-cache madison teamcity sudo apt install teamcity=<VERSION_BEFORE_2026.1> sudo apt-mark hold teamcity

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list teamcity sudo dnf downgrade teamcity-<VERSION_BEFORE_2026.1> sudo dnf versionlock add teamcity

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora 46 · gnome-shell-extension-tiling-assistant · FIXED · 56-1.fc46 · FEDORA-2026-ebf66a5321 · source

sudo dnf upgrade --advisory=FEDORA-2026-ebf66a5321

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: sfewer-r7/CVE-2026-63077 (20 stars)
GitHub PoC: unveiledhistory49/teamcity-cve-2026-63077-remediation (0 stars)
GitHub PoC: BoredHackerBlog/teamcity-CVE-2026-63077-pcap (0 stars)
Metasploit: JetBrains TeamCity Agent Polling Unauthenticated Remote Code Execution
Nuclei scan template: JetBrains TeamCity < 2026.1.3, 2025.11.7 - Remote Code Execution

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-63077?

teamcity: upgrade to 2025.11.7, 2026.1.3. Exact commands for each OS are on this page.

Is CVE-2026-63077 being exploited?

Yes. CVE-2026-63077 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2026-63077 affect?

CVE-2026-63077 affects teamcity. Severity is critical (CVSS 9.8). In JetBrains TeamCity before 2026.1.3, 2025.11.7 unauthenticated remote code execution was possible via the agent polling protocol

How urgent is CVE-2026-63077?

Priority 100/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Used in ransomware campaigns; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-65906 HIGH 8.8 UPGRADE In JetBrains TeamCity before 2026.1.2, 2025.11.6 сode execution via Kotlin DSL sandbox escape was possible

References

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