{"id":"CVE-2026-53503","aliases":["GHSA-cqjp-jf4r-h5q9","PYSEC-2026-3619"],"url":"https://o3.security/vulnerability/CVE-2026-53503","summary":"Thumbor convolution filter allows divide-by-zero in C extension leading to remote DoS","details":"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.","published":"2026-07-31T18:54:20.747Z","modified":"2026-09-10T08:13:47.877912Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00412,"percentile":0.34723,"asOf":"2026-09-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"thumbor","fixedVersion":"7.8.0"}],"fix":{"url":"https://github.com/thumbor/thumbor/commit/447e192e3fb92e64c12e5354a56a4a7133f69d73","label":"thumbor/thumbor@447e192"},"references":[{"type":"WEB","url":"https://github.com/thumbor/thumbor/releases/tag/7.8.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53503.json"},{"type":"ADVISORY","url":"https://github.com/thumbor/thumbor/security/advisories/GHSA-cqjp-jf4r-h5q9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53503"},{"type":"FIX","url":"https://github.com/thumbor/thumbor/commit/447e192e3fb92e64c12e5354a56a4a7133f69d73"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-10T08:13:47.877912Z"}}