Image-processing stall via exponential regex backtracking
Published Jul 31, 2026 · Updated Jul 31, 2026
Regular expression denial of service in Thumbor before 7.8.0 allows remote attackers to stall image processing via a crafted URL. The convolution filter parser applies re.match to an ambiguous repeated-number pattern that backtracks exponentially on malformed semicolon-delimited input. No authentication or user interaction is required; one request occupies a processing worker until matching returns, leaving new images assigned to that worker unprocessed.
Summary
What happened
Regular expression denial of service in Thumbor before 7.8.0 allows remote attackers to stall image processing via a crafted URL. The convolution filter parser applies re.match to an ambiguous repeated-number pattern that backtracks exponentially on malformed semicolon-delimited input. No authentication or user interaction is required; one request occupies a processing worker until matching returns, leaving new images assigned to that worker unprocessed.
The record
- CVE
- CVE-2026-53504
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Vendor
- thumbor
- Product
- thumbor
- Classifications
- CWE-400, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 31, 2026CVE publishedPublication date reported by the CVE source.
- Jul 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 7.8.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA convolution-filter proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo