{"id":"CVE-2026-53504","aliases":["GHSA-5vjc-7cxw-4w6j","PYSEC-2026-3616"],"url":"https://o3.security/vulnerability/CVE-2026-53504","summary":"Thumbor has Regex Denial of Service (ReDoS) in `convolution` filter","details":"### Summary\nThe regular expression used to parse the `convolution` filter exhibits exponential-time backtracking for certain inputs, enabling a Regular Expression Denial of Service (ReDoS).\n\n### Details\nThe RegExp for `convolution` is defined as `convolution\\((?:\\s*((?:[-]?[\\d]+\\.?[\\d]*[;])*(?:[-]?[\\d]+\\.?[\\d]*))\\s*)(?:,\\s*([\\d]+)\\s*)(?:,\\s*([Tt]rue|[Ff]alse|1|0)\\s*)?\\)`. Within this expression a dangerous subpattern effectively behaves like `(\\d+)*,\\d+`.\n\n### PoC\nA filter string containing many repeated values will exhaust `re.match`:\n- `convolution(-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11)`\n- http://localhost:8888/unsafe/0x0/smart/filters:convolution(-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11)/x.png\n\nThe evaluation occurs on https://github.com/thumbor/thumbor/blob/master/thumbor/filters/__init__.py#L189.\n\n### Impact\nA specially crafted URL will lead to denial of service, as new images won't be processed until `re.match` returns.","published":"2026-07-31T18:57:19.257Z","modified":"2026-10-28T02:30:29.307815990Z","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":0.00406,"percentile":0.34195,"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/3f38fe1610d20168e91f76d432212de30727eb2e","label":"thumbor/thumbor@3f38fe1"},"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-2026-53504.json"},{"type":"ADVISORY","url":"https://github.com/thumbor/thumbor/security/advisories/GHSA-5vjc-7cxw-4w6j"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53504"},{"type":"FIX","url":"https://github.com/thumbor/thumbor/commit/3f38fe1610d20168e91f76d432212de30727eb2e"},{"type":"PACKAGE","url":"https://github.com/thumbor/thumbor"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:29.307815990Z"}}