{"id":"CVE-2026-33418","aliases":["GHSA-7j2x-32w6-p43p"],"url":"https://o3.security/vulnerability/CVE-2026-33418","summary":"@dicebear/converter ensureSize() Vulnerable to SVG Dimension Capping Bypass via XML Comment Injection","details":"## Summary\n\nThe `ensureSize()` function in `@dicebear/converter` used a regex-based approach to rewrite SVG `width`/`height` attributes, capping them at 2048px to prevent denial of service. This size capping could be bypassed by crafting SVG input that causes the regex to match a non-functional occurrence of `<svg` before the actual SVG root element. When the SVG is subsequently rendered via `@resvg/resvg-js` on the Node.js code path, it renders at the attacker-specified dimensions, potentially causing out-of-memory crashes.\n\n## Details\n\nThe vulnerable function used `String.prototype.replace()` with a non-global regex to find and rewrite the first `<svg` tag's dimensions. Since the regex does not distinguish between `<svg` appearing inside non-element XML constructs and the actual SVG root element, a crafted input can cause the regex to match a decoy instead of the real element, leaving the actual SVG dimensions unclamped.\n\nIn the Node.js rendering path, `renderAsync` from `@resvg/resvg-js` was called without a `fitTo` constraint, so it would render at whatever dimensions the SVG element specified — potentially allocating gigabytes of memory.\n\nThe browser code path is **not** vulnerable because it uses the clamped `size` return value from `ensureSize()` to set `canvas.width` and `canvas.height` directly.\n\n## Impact\n\nAny application that passes untrusted or user-supplied SVG content through `@dicebear/converter`'s Node.js conversion functions (`toPng`, `toJpeg`, `toWebp`, `toAvif`) is vulnerable to denial of service via excessive memory allocation. Note that `@dicebear/converter` can be used independently of DiceBear's avatar generation — any SVG string can be passed to the conversion functions.\n\nThe impact is limited to availability — there is no data disclosure or integrity impact. The browser code path is not affected.\n\n## Fix\n\nThe regex-based approach has been replaced with XML-aware processing using `fast-xml-parser` to correctly identify and modify the SVG root element's attributes. Additionally, a `fitTo` constraint has been added to the `renderAsync` call as defense-in-depth, ensuring the rendered output is always bounded regardless of SVG content.","published":"2026-03-24T13:25:57.540Z","modified":"2026-08-12T03:51:31.670385912Z","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":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@dicebear/converter","fixedVersion":"9.4.2"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33418.json"},{"type":"ADVISORY","url":"https://github.com/dicebear/dicebear/security/advisories/GHSA-7j2x-32w6-p43p"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33418"},{"type":"PACKAGE","url":"https://github.com/dicebear/dicebear"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:31.670385912Z"}}