CVE-2026-53501 Thumbor has HMAC validation bypass via multiple .replace() calls when removing URL signature

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...