Arbitrary file read via post-validation path decoding
Published Jul 31, 2026 · Updated Jul 31, 2026
Path traversal in thumbor before 7.8.0 allows remote attackers to read server files via crafted watermark or frame filter paths. The file_loader calls unquote() only after abspath() and startswith() approve an encoded path, turning accepted %2e%2e segments into parent-directory traversal. Exploitation requires file_loader or its HTTP fallback; unsafe URLs and the watermark and frame filters are enabled by default, exposing readable files outside FILE_LOADER_ROOT_PATH.
Summary
What happened
Path traversal in thumbor before 7.8.0 allows remote attackers to read server files via crafted watermark or frame filter paths. The file_loader calls unquote() only after abspath() and startswith() approve an encoded path, turning accepted %2e%2e segments into parent-directory traversal. Exploitation requires file_loader or its HTTP fallback; unsafe URLs and the watermark and frame filters are enabled by default, exposing readable files outside FILE_LOADER_ROOT_PATH.
The record
- CVE
- CVE-2026-53502
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Vendor
- thumbor
- Product
- thumbor
- Classifications
- CWE-22, T1005, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 31, 2026CVE publishedPublication date reported by the CVE source.
- Jul 31, 2026Record 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=< 7.8.0
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
- GHSA-cj54-hpcc-gj6h curl proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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