Thumbor proportion filter allows unbounded post-transform resize leading to remote DoS — GHSA-PHJ3-59PF-CP83

Summary

### Summary Thumbor's `filters:proportion(<value>)` filter does not enforce an upper bound on `<value>` and runs in the post-transform phase. An attacker can trigger extremely large resizes (CPU/memory exhaustion) and cause denial of service. ### Details - Filter implementation: `thumbor/filters/proportion.py` - `value` is parsed as a float (`BaseFilter.DecimalNumber`) with no maximum. - The filter computes…

Timeline

Published by source

2026-07-31

Risk context

• Reported severity or threat level: high.
• Review exposure for the affected product or family: pip: thumbor.

Product

pip: thumbor

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-PHJ3-59PF-CP83

Source

GitHub

Vendor

GitHub

Published by source

2026-07-31

Last source activity

2026-07-31

Additional identifiers

CVE-2026-53505

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.