CVE-2023-27577

Workarounds

Users can mitigate the vulnerability by ensuring that their admin accounts are secured with strong passwords and other best practices for account security. Additionally, users can limit the exposure of sensitive files on the server by implementing appropriate file permissions and access controls.

If an admin account has already been compromised by an attacker, the LESS parser can be exploited to read sensitive files on the server through the use of path traversal techniques.

An attacker can achieve this by providing an absolute path to a sensitive file in the custom LESS setting, which the LESS parser will then read. For example, an attacker could use the following code to read the contents of the /etc/passwd file:

@import (inline) '/etc/passwd';

.test {
  content: data-uri('/etc/passwd');
}

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2023-27577 has a CVSS score of 6.5 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.7.0); upgrading removes the vulnerable code path.

Kodem intelligence

The vulnerability has been addressed in version 1.7. Users should upgrade to this version to mitigate the vulnerability.

1. What is CVE-2023-27577? CVE-2023-27577 is a medium-severity path traversal vulnerability in flarum/core (composer), affecting versions < 1.7.0. It is fixed in 1.7.0. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2023-27577? CVE-2023-27577 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of flarum/core are affected by CVE-2023-27577? flarum/core (composer) versions < 1.7.0 is affected.
4. Is there a fix for CVE-2023-27577? Yes. CVE-2023-27577 is fixed in 1.7.0. Upgrade to this version or later.
5. Is CVE-2023-27577 exploitable, and should I be worried? Whether CVE-2023-27577 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-27577 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-27577? Upgrade flarum/core to 1.7.0 or later.