Thumbor convolution filter allows divide-by-zero in C extension leading to remote DoS

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-53503
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-31 19:17:09 UTC
Updated2026-07-31 19:17:09 UTC
DescriptionThumbor 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-20 | CWE-369 | CWE-20 CWE-20: Improper Input Validation | CWE-369 CWE-369: Divide By Zero

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Thumbor Thumbor affected < 7.8.0 Not specified

References

ReferenceSourceLinkTags
github.com/thumbor/thumbor/releases/tag/7.8.0 [email protected] github.com
github.com/thumbor/thumbor/security/advisories/GHSA-cqjp-jf4r-h5q9 [email protected] github.com
github.com/thumbor/thumbor/commit/447e192e3fb92e64c12e5354a56a4a7133f69d73 [email protected] github.com
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