8.2 CVE-2026-53501
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.
https://nvd.nist.gov/vuln/detail/CVE-2026-53501
Categories
CWE-347 : Improper Verification of Cryptographic Signature
The product does not verify, or incorrectly verifies, the cryptographic signature for data. Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Does not properly verify signatures for "trusted" entities. Insufficient verification allows spoofing. Insufficient verification allows spoofing. Accepts a configuration file without a Message Integrity Check (MIC) signature.
References
security-advisories@github.com
AFFECTED (from MITRE)
| Vendor |
Product |
Versions |
| thumbor |
thumbor |
|
| © 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. |
CPE
REMEDIATION
EXPLOITS
Exploit-db.com
| id |
description |
date |
|
| No known exploits |
POC Github
Other Nist (github, ...)
CAPEC
Common Attack Pattern Enumerations and Classifications
| id |
description |
severity |
| 463 |
Padding Oracle Crypto Attack
An adversary is able to efficiently decrypt data without knowing the decryption key if a target system leaks data on whether or not a padding error happened while decrypting the ciphertext. A target system that leaks this type of information becomes the padding oracle and an adversary is able to make use of that oracle to efficiently decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block). In addition to performing decryption, an adversary is also able to produce valid ciphertexts (i.e., perform encryption) by using the padding oracle, all without knowing the encryption key. |
High |
| 475 |
Signature Spoofing by Improper Validation
An adversary exploits a cryptographic weakness in the signature verification algorithm implementation to generate a valid signature without knowing the key. |
High |
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