CVE-2023-42793
CVE-2023-42793 is a security flaw in JetBrains TeamCity, software that builds and tests code. Attackers can run their own code on JetBrains TeamCity. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 4 Oct 2023, 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 2023.05.4 of TeamCity.
Description
CISA calls it an authentication bypass in JetBrains TeamCity. In its words: “JetBrains TeamCity contains an authentication bypass vulnerability that allows for remote code execution on TeamCity Server.”[1]
The underlying weakness is authentication bypass (CWE-288), in MITRE’s list of common software weaknesses.[2]
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, 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 | 2023.05.4 |
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 4 Oct 2023, 15 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 25 Oct 2023 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 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 2023.05.4 of TeamCity), or not in use. CISA gave US government agencies until 25 Oct 2023 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 9.8.[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-2024-27199: relative path traversal ·
- CVE-2024-27198: authentication bypass ·
Other authentication bypass flaws
- CVE-2026-20079, Cisco Secure Firewall Management Center (FMC) and Security Cloud Control (SCC) Firewall Management: firewall management center authentication bypass using an alternate path or channel ·
- CVE-2026-19490, Citrix NetScaler: authentication bypass using an alternate path or channel ·
- CVE-2026-18556, N-able N-central: authentication bypass using an alternate path or channel ·
- CVE-2026-18577, N-able N-central: authentication bypass using an alternate path or channel ·
- CVE-2026-1603, Ivanti Endpoint Manager (EPM): authentication bypass ·
Added the same day
- CVE-2023-28229, Microsoft Windows CNG Key Isolation Service: privilege escalation ·
Every JetBrains flaw on CISA’s list · Everything added in October 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “JetBrains TeamCity Authentication Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 4 Oct 2023.
- ^ National Institute of Standards and Technology. “CVE-2023-42793 Detail”. National Vulnerability Database, published 19 Sep 2023.
- ^ JetBrains. Advisories and fixes: blog.jetbrains.com, blog.jetbrains.com, jetbrains.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 1.000, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2023-42793”. 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.