Server file disclosure via unsafe LESS imports
Published Mar 10, 2023 · Updated Feb 25, 2025
Path traversal in the custom LESS setting in Flarum before 1.7.0 allows remote authenticated users to read server files. The custom LESS validator accepts absolute paths in @import and data-uri directives, and the parser embeds file contents in generated CSS. Administrator access is required, and disclosure is limited to files readable by the PHP process.
Summary
What happened
Path traversal in the custom LESS setting in Flarum before 1.7.0 allows remote authenticated users to read server files. The custom LESS validator accepts absolute paths in @import and data-uri directives, and the parser embeds file contents in generated CSS. Administrator access is required, and disclosure is limited to files readable by the PHP process.
The record
- CVE
- CVE-2023-27577
- Published
- Mar 10, 2023
- Updated
- Feb 25, 2025
- Vendor
- Flarum
- Product
- Flarum
- Classifications
- CWE-22, T1005
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Mar 10, 2023CVE publishedPublication date reported by the CVE source.
- Feb 25, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.7.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream custom LESS file-read payloadproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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