CVE-2024-9026

In PHP versions 8.1.* before 8.1.30, 8.2.* before 8.2.24, 8.3.* before 8.3.12, when using PHP-FPM SAPI and it is configured to catch workers output through catch_workers_output = yes, it may be possible to pollute the final log or remove up to 4 characters from the log messages by manipulating log message content. Additionally, if PHP-FPM is configured to use syslog output, it may be possible to further remove log data using the same vulnerability.

Weakness

The product does not neutralize or incorrectly neutralizes output that is written to logs.

Affected Software

Extended Description

This can allow an attacker to forge log entries or inject malicious content into logs. Log forging vulnerabilities occur when:

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.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/268.html
• https://cwe.mitre.org/data/definitions/81.html
• https://cwe.mitre.org/data/definitions/93.html

References

• https://github.com/php/php-src/security/advisories/GHSA-865w-9rf3-2wh5