CVE-2026-53501
Description
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Fixed 2 releases
| Version | Status | Fixed in |
|---|---|---|
| sid | Fixed | 7.8.0-1 |
| forky | Fixed | 7.8.0-1 |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| PyPI | thumbor | <7.8.0 | 7.8.0 |
References
- https://github.com/thumbor/thumbor/commit/e3ae3e2500537b4d735df4144129a649374bb70b
- https://github.com/thumbor/thumbor/releases/tag/7.8.0
- https://github.com/thumbor/thumbor/security/advisories/GHSA-mw3h-qjxj-6xg9
- https://github.com/thumbor/thumbor
- https://security-tracker.debian.org/tracker/CVE-2026-53501
CWEs
CWE-347
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.