Improper Verification of Cryptographic Signature Affecting thumbor package, versions <7.8.0-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-THUMBOR-18492953
- published1 Aug 2026
- disclosed31 Jul 2026
Introduced: 31 Jul 2026
CVE-2026-53501 (opens in a new tab)How to fix?
Upgrade Debian:unstable thumbor to version 7.8.0-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream thumbor package and not the thumbor package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
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.