Vulnerability 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/thumbor/thumbor/commit/447e192e3fb92e64c12e5354a56a4a7133f69d
- https://github.com/thumbor/thumbor/releases/tag/7.8.0
- https://github.com/thumbor/thumbor/security/advisories/GHSA-cqjp-jf4r-h5q9
- https://github.com/thumbor/thumbor/security/advisories/GHSA-cqjp-jf4r-h5q9
FAQ
What is CVE-2026-53503?
CVE-2026-53503 is a vulnerability with a CVSS score of 7.5 (HIGH). 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...
How severe is CVE-2026-53503?
CVE-2026-53503 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-53503?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.