---
id: CVE-2026-53501
title: Thumbor is an open-source photo thumbnail service by globo.com
summary: >-
  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() …
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L'
cwe:
  - CWE-347
vendor: thumbor
product: thumbor
affected:
  - thumbor <= 7.7.7
patched:
  - thumbor 7.8.0
published: '2026-07-31'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:51:43.490'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53501'
references:
  - url: >-
      https://github.com/thumbor/thumbor/commit/e3ae3e2500537b4d735df4144129a649374bb70b
    label: security-advisories@github.com
  - url: 'https://github.com/thumbor/thumbor/releases/tag/7.8.0'
    label: security-advisories@github.com
  - url: 'https://github.com/thumbor/thumbor/security/advisories/GHSA-mw3h-qjxj-6xg9'
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-mw3h-qjxj-6xg9'
tags:
  - nvd
  - ghsa
  - pip
epss: 0.00208
epssPercentile: 0.11253
aliases:
  - GHSA-mw3h-qjxj-6xg9
ecosystem: pip
ingestedAt: '2026-07-31T19:01:36.572Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-53501)

Affected packages:

- `thumbor <= 7.7.7`

Patched in:

- `thumbor 7.8.0`

Source: https://github.com/advisories/GHSA-mw3h-qjxj-6xg9