high7.5
CVE-2026-53503
Thumbor convolution filter allows divide-by-zero in C extension leading to remote DoS
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | thumbor | <= 7.7.7 | 7.8.0 |