CVE-2024-27199
CVE-2024-27199 is a security flaw in JetBrains TeamCity, software that builds and tests code. Attackers can read files on JetBrains TeamCity that should be out of reach. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 20 Apr 2026, and says ransomware gangs have used it.[1]
JetBrains TeamCity is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 2023.11.4 of TeamCity.
Description
CISA calls it a relative path traversal in JetBrains TeamCity. In its words: “JetBrains TeamCity contains a relative path traversal vulnerability that could allow limited admin actions to be performed.”[1]
The underlying weakness is CWE-23, in MITRE’s list of common software weaknesses.[2]
It scores 7.3 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| TeamCity | 2023.11.4 |
Most families won’t have JetBrains TeamCity; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 20 Apr 2026, 777 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 4 May 2026 to fix it.[1] CISA says ransomware gangs have used it.
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
JetBrains has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.JetBrains TeamCity is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 2023.11.4 of TeamCity), or not in use. CISA gave US government agencies until 4 May 2026 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.3.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[4] |
See also
Other JetBrains TeamCity flaws
- CVE-2026-63077: deserialization of untrusted data ·
- CVE-2024-27198: authentication bypass ·
- CVE-2023-42793: authentication bypass ·
Similar flaws
- CVE-2026-76519, Cisco Secure Email Gateway: relative path traversal ·
- CVE-2026-34926, Trend Micro Apex One: (on-premise) directory traversal ·
- CVE-2025-64446, Fortinet FortiWeb: path traversal ·
- CVE-2022-37042, Synacor Zimbra Collaboration Suite (ZCS): authentication bypass ·
- CVE-2021-38163, SAP NetWeaver: unrestricted file upload ·
Added the same day
- CVE-2026-20133, Cisco Catalyst SD-WAN Manager: exposure of sensitive information to an unauthorized actor ·
- CVE-2026-20128, Cisco Catalyst SD-WAN Manager: storing passwords in a recoverable format ·
- CVE-2026-20122, Cisco Catalyst SD-WAN Manger: catalyst SD-WAN manager incorrect use of privileged APIs ·
- CVE-2025-48700, Synacor Zimbra Collaboration Suite (ZCS): cross-site scripting ·
- CVE-2025-32975, Quest KACE Systems Management Appliance (SMA): improper authentication ·
Every JetBrains flaw on CISA’s list · Everything added in April 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “JetBrains TeamCity Relative Path Traversal Vulnerability”. Known Exploited Vulnerabilities Catalog, added 20 Apr 2026.
- ^ National Institute of Standards and Technology. “CVE-2024-27199 Detail”. National Vulnerability Database, published 4 Mar 2024.
- ^ JetBrains. Advisories and fixes: jetbrains.com, blog.jetbrains.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 1.000, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2024-27199”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.