CISA: Ransomware gangs now exploiting critical TeamCity flaw
Source Bleeping Computer
Exploited in the wild · KEV due 8 Aug 2026 · public exploit available (Metasploit) : upgrade to 2026.1.3 now.
Data as of 6 Nov 2026, 23:24 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
- Patch
- Available – fixed in 2026.1.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 27 Jul 2026
Detectable: evidence found.
nuclei template: JetBrains TeamCity < 2026.1.3, 2025.11.7 - Remote Code Execution
Weaponized: evidence found.
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 9 days after disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by JetBrains s.r.o.
, 12 days before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 23 minutes after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed · ransomware use known
, 9 days after disclosure
KEV remediation due
US federal deadline
, 12 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.
What to do
Upgrade TeamCity to 2026.1.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| JetBrainsTeamCity | Affected
| Fixed in
|
AI-suggested
JetBrains released an official patch on July 25, 2026, for TeamCity On-Premises versions 2025.11.7 and 2026.1.3. Immediate application of these patches is strongly recommended. For environments where immediate patching is not possible, JetBrains advises restricting TeamCity server access to trusted networks only. CISA has mandated U.S. federal agencies to patch within three days of the advisory. Monitoring vendor advisories for updates and applying patches promptly is critical to mitigate ongoing exploitation.
Description
A critical authentication bypass vulnerability (CVE-2026-63077) in JetBrains TeamCity allows unauthenticated attackers with HTTP(S) access to execute arbitrary operating system commands. This flaw was patched in July 2026 in TeamCity On-Premises versions 2025.11.7 and 2026.1.3. Despite the patch, ransomware gangs are actively exploiting this vulnerability, as confirmed by CISA and JetBrains. The vulnerability enables attackers to bypass authentication via the TeamCity agent polling protocol, potentially compromising server data, configurations, credentials, and build artifacts. CISA has added this vulnerability to its Known Exploited Vulnerabilities Catalog and mandated federal agencies to patch within three days. Shadowserver reports over 160 unpatched Internet-exposed TeamCity servers remain vulnerable. JetBrains urges immediate patching or restricting access to trusted networks.