CVE-2026-53500
Received Received - Intake

Thumbor Path Traversal via Unescaped Dots in ALLOWED_SOURCES

Publication date: 2026-07-31

Last updated on: 2026-07-31

Assigner: GitHub, Inc.

Description
Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, the ALLOWED_SOURCES configuration passes plain strings to re.match() without escaping dots, so a hostname differing at dot positions can match the allowlist. This issue is fixed in 7.8.0.

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Meta Information

Published
2026-07-31
Last Modified
2026-07-31
Generated
2026-08-01
AI Q&A
2026-07-31
EPSS Evaluated
N/A
NVD
CVE-2026-53500
EUVD
EUVD-2026-51597

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
globo.com thumbor to 7.8.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

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Executive Summary

Thumbor before 7.8.0 has a flaw in the ALLOWED_SOURCES configuration. It passes plain strings to re.match() without escaping dots, allowing hostnames that differ only at dot positions to incorrectly match the allowlist.

Detection Guidance

To detect this vulnerability, check if your Thumbor version is below 7.8.0. Run: thumbor --version. If the version is older, the system is vulnerable. Additionally, review ALLOWED_SOURCES configuration for improper use of dots in hostnames that could allow bypassing restrictions.

Impact Analysis

An attacker could bypass the intended hostname restrictions and access unauthorized resources through Thumbor. This could lead to information disclosure or unauthorized actions depending on Thumbor's usage.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, potentially violating GDPR's data protection requirements or HIPAA's access controls. Organizations using Thumbor may face compliance violations if exploited.

Mitigation Strategies

Upgrade Thumbor to version 7.8.0 or later to address the ALLOWED_SOURCES configuration issue.

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