CVE-2026-53504 Thumbor has Regex Denial of Service (ReDoS) in `convolution` filter
Attackers can cause denial of service in Thumbor by sending crafted URLs to the convolution filter, exhausting server resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53504?
CVE-2026-53504 is a high-severity denial of service vulnerability in thumbor, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, the convolution filter regular expression performs exponential backtracking on crafted repeated numeric input, allowing a URL request to exhaust processing time. This issue is fixed in 7.8.0.
Weakness: CWE-400
Which versions are affected by CVE-2026-53504?
3 open source packages ship an affected version, including thumbor.
| Package | Affected | Fixed in |
|---|---|---|
thumbor PyPI | All versions | 7.8.0 |
thumbor PyPI | All versions | 7.8.0 |
thumbor PyPI | All versions | 7.8.0 |
How do I fix CVE-2026-53504?
Upgrade thumbor to 7.8.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-53504 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53504 exists.
Sources
Also known as DEBIAN-CVE-2026-53504, GHSA-5vjc-7cxw-4w6j, PYSEC-2026-3616, UBUNTU-CVE-2026-53504.