CVE-2026-53503
Thumbor convolution filter allows divide-by-zero in C extension leading to remote DoS
- State
- Published
- Severity
- 7.5 High
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Reserved
- Jun 9, 2026
Description
Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, Thumbor's filters:convolution(<matrix>, <columns>, <should_normalize>) filter passes the user-controlled <columns> value to a C extension (thumbor/ext/filters/_convolution.c) where it is used as a divisor (for % and /) without validating columns > 0. When columns=0, the C code triggers undefined behavior; on x86_64 this reliably results in a fatal divide-by-zero trap (SIGFPE) and crashes the Thumbor process, causing a remote denial of service. This issue is fixed in 7.8.0.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
thumborthumbor |
|
References
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