Quick answers
- Is CVE-2026-53505 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-53505 being exploited in the wild.
- How severe is CVE-2026-53505?
- High severity, with a CVSS score of 7.5, published 31 July 2026.
- Which products and versions are affected?
- thumbor (PyPI) <= 7.7.7, ECOSYSTEM:introduced=0,fixed=7.8.0.
- Is there a fix for CVE-2026-53505?
- Yes. thumbor (PyPI): upgrade to 7.8.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-53505 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-53505?
- Check whether you run thumbor (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- thumbor (PyPI): upgrade to 7.8.0 or later
pip install "thumbor>=7.8.0"
Technical details
A vulnerability exists in Thumbor's 'filters:proportion(<value>)' implementation where the input value is parsed as an unbounded float. Because this filter executes during the POST_TRANSFORM phase, it bypasses standard request-level size clamping (such as MAX_WIDTH and MAX_HEIGHT). An attacker can provide a large value (e.g., 10000) to trigger an arbitrarily large resize operation, leading to CPU and memory exhaustion. This is exploitable via unauthenticated network requests if 'unsafe' URLs are enabled, or by any user capable of generating or obtaining a valid signed URL. The issue is resolved in version 7.8.0 by enforcing a strict bound on the proportion parameter.
Affected products
- thumbor thumbor <= 7.7.7
Identifiers
- CVE-2026-53505
- GHSA-phj3-59pf-cp83
- PYSEC-2026-3621
Timeline
- 2026-05-30: patched: Version 7.8.0 released
- 2026-06-10: advisory: GitHub Security Advisory published
- 2026-07-31: disclosed: CVE published to NVD