CVE-2023-42793
In JetBrains TeamCity before 2023.05.4 authentication bypass leading to RCE on TeamCity Server was possible
Critical
Known exploited
- Severity
- 9.8 / 10
- Critical · CVSS 3.1
- Exploit chance (EPSS)
- 99.99%
- Chance of exploitation in the next 30 days. Higher than 99.98% of scored vulnerabilities.
- Known exploited
- Yes
- In CISA's catalog since Oct 4, 2023
- Weakness
- CWE-288 Authentication Bypass Using an Alternate Path or Channel
- CWE-306 Missing Authentication for Critical Function
- Fix
- None yet
- No fixed version published
Exploited in the wild. JetBrains TeamCity Authentication Bypass Vulnerability (JetBrains TeamCity). Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Due for U.S. federal agencies by Oct 25, 2023. Known to be used in ransomware campaigns.
Description
In JetBrains TeamCity before 2023.05.4 authentication bypass leading to RCE on TeamCity Server was possible
How to fix
No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.
Severity breakdown
CVSS 3.1 9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-288: Authentication Bypass Using an Alternate Path or Channel
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
How to prevent it
- Architecture and Design: Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
CWE-306: Missing Authentication for Critical Function
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
How to prevent it
- Architecture and Design: Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability. Identify all potential communication channels, or other means of interaction with the software, to ensure that all channels are appropriately protected, including those channels that are assumed to be accessible only by authorized parties. Developers sometimes perform authentication at the primary channel, but open up a secondary channel that is assumed to be private. For example, a login mechanism may be listening on one network port, but after successful authentication, it may open up a second port where it waits for the connection, but avoids authentication because it assumes that only the authenticated party will connect to the port. In general, if the software or protocol allows a single session or user state to persist across multiple connections or channels, authentication and appropriate credential management need to be used throughout.
- Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Architecture and Design: Where possible, avoid implementing custom, "grow-your-own" authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These capabilities may avoid common weaknesses that are unique to authentication; support automatic auditing and tracking; and make it easier to provide a clear separation between authentication tasks and authorization tasks. In environments such as the World Wide Web, the line between authentication and authorization is sometimes blurred. If custom authentication routines are required instead of those provided by the server, then these routines must be applied to every single page, since these pages could be requested directly.
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator [REF-45].
- Implementation, System Configuration, Operation: When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data [REF-1297] [REF-1298] [REF-1302].
References
Advisories
- packetstormsecurity.com/files/174860/JetBrains-TeamCity-Unauthenticated-Remote-Code-Executio…
- attackerkb.com/topics/1XEEEkGHzt/cve-2023-42793
- blog.jetbrains.com/teamcity/2023/09/cve-2023-42793-vulnerability-post-mortem
- jetbrains.com/privacy-security/issues-fixed
- rapid7.com/blog/post/2023/09/25/etr-cve-2023-42793-critical-authentication-bypa…
- sonarsource.com/blog/teamcity-vulnerability
Other links
Timeline
- Published
- Added to CISA's Known Exploited Vulnerabilities catalog
- Remediation due for U.S. federal agencies
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-vc32-4gwf-77xp Nginx UI: OTP secure-session step-up can be bypassed via MCP configuration tools | High | Same weakness, CWE-288 |
| GHSA-hxcx-9h4f-42xx Snipe-IT: 2FA bypass via the API token flow | High | Same weakness, CWE-288 |
| GHSA-pf83-w3f9-8m37 n8n: Disabled OIDC SSO Endpoints Remain Active and Issue Valid Sessions | Medium | Same weakness, CWE-288 |
| GHSA-p68q-wchp-6fh7 fastify vulnerable to authentication bypass via malformed URLs reaching encapsulated not-found handlers | High | Same weakness, CWE-288 |
| CVE-2026-19490 Vulnerability in NetScaler ADC and NetScaler Gateway. | Critical Known exploited | Same weakness, CWE-288 |
| GHSA-7j72-f6wg-cxw6 SiYuan: Anonymous publish-password authentication bypass via getHeadingChildrenDOM / getHeading*Transaction / getBacklinkDoc (publish mode) | Critical | Same weakness, CWE-288 |
| CVE-2026-18577 An incomplete patch for CVE-2026-18556 allows for authentication bypass and account takeover in N-central Versions through 2026.3.1 | High Known exploited | Same weakness, CWE-288 |
| CVE-2026-18556 Authentication bypass using an alternate path or channel vulnerability in N-able N-central allows Authentication Bypass. | High Known exploited | Same weakness, CWE-288 |
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