CVE-2026-33418

The 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.

Details

The 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.

In 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.

The browser code path is not vulnerable because it uses the clamped size return value from ensureSize() to set canvas.width and canvas.height directly.

Any 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.

The impact is limited to availability, there is no data disclosure or integrity impact. The browser code path is not affected.

CVE-2026-33418 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.4.2); upgrading removes the vulnerable code path.

Kodem intelligence

The 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.

1. What is CVE-2026-33418? CVE-2026-33418 is a high-severity security vulnerability in @dicebear/converter (npm), affecting versions <= 9.4.1. It is fixed in 9.4.2.
2. How severe is CVE-2026-33418? CVE-2026-33418 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @dicebear/converter are affected by CVE-2026-33418? @dicebear/converter (npm) versions <= 9.4.1 is affected.
4. Is there a fix for CVE-2026-33418? Yes. CVE-2026-33418 is fixed in 9.4.2. Upgrade to this version or later.
5. Is CVE-2026-33418 exploitable, and should I be worried? Whether CVE-2026-33418 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-33418 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-33418? Upgrade @dicebear/converter to 9.4.2 or later.