CubeAPM nightly-2025-08-01-1 allow unauthenticated attackers to inject arbitrary log entries into production systems via the /api/logs/insert/elasticsearch/_bulk endpoint. This endpoint accepts bulk log data without requiring authentication or input validation, allowing remote attackers to perform unauthorized log injection. Exploitation may lead to false log entries, log poisoning, alert obfuscation, and potential performance degradation of the observability pipeline. The issue is present in the core CubeAPM platform and is not limited to specific deployment configurations.
Weakness
The product constructs a log message from external input, but it does not neutralize or incorrectly neutralizes special elements when the message is written to a log file.
Potential Mitigations
- Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
References