globo.com Thumbor up to 7.7.x HMAC Validation replace improper authentication

Summaryinfo

A vulnerability marked as problematic has been reported in globo.com Thumbor up to 7.7.x. This affects the function replace of the component HMAC Validation. This manipulation causes improper authentication. This vulnerability appears as CVE-2026-53501. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability has been found in globo.com Thumbor up to 7.7.x and classified as problematic. Affected by this vulnerability is the function replace of the component HMAC Validation. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-53501 since 06/09/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 7.8.0 eliminates this vulnerability.

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Productinfo

Vendor

• globo.com

Name

• Thumbor

Version

• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7

CPE 2.3info

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CPE 2.2info

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