CVE-2026-53501 Details
Description
Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, Thumbor’s HMAC validation can be bypassed due to the use of Python’s .replace() when removing the signature from the URL before validation. Since .replace() removes all occurrences of the substring, an attacker can insert the same signature multiple times in the URL and manipulate the final URL used for validation. This allows crafting URLs where the validated string differs from the actual requested resource, enabling loading images from unintended domains or paths. This issue is fixed in 7.8.0.
A vulnerability in Thumbor, an open-source photo thumbnail service, allows for bypassing HMAC validation in versions prior to 7.8.0. The issue arises from using Python's .replace() method to remove the signature from the URL before validation. This method removes all instances of the substring, enabling an attacker to inject the same signature multiple times and manipulate the URL used for validation. As a result, crafted URLs can be created where the validated string does not match the actual requested resource, potentially leading to loading images from unintended domains or paths.
Users are advised to upgrade to Thumbor version 7.8.0, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 31, 2026CISA-ADP
Assessed Jul 31, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/thumbor/thumbor/commit/e3ae3e2500537b4d735df4144129a649374bb70b | [email protected] | Source CodeVendor |
| https://github.com/thumbor/thumbor/releases/tag/7.8.0 | [email protected] | Release NotesVendor |
| https://github.com/thumbor/thumbor/security/advisories/GHSA-mw3h-qjxj-6xg9 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-347 | Improper Verification of Cryptographic Signature | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Thumbor | <= 7.7.7 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 31, 2026 | CVE Modified | CISA-ADP |
| Jul 31, 2026 | New CVE Received | [email protected] |