CVE-2026-6968

# Conceptual PoC for Path Traversal in awslabs/tough (CVE-2026-6968) # This demonstrates the logic flaw where path validation is missing. import os def vulnerable_write(base_dir, user_controlled_filename, content): # Simulating the vulnerable behavior in tough < v0.22.0 # The code joins the path but fails to verify the resolved path is still within base_dir. # Scenario 1: Absolute path usage (if input allows absolute paths) # If user_controlled_filename is "/etc/malicious", os.path.join might ignore base_dir depending on implementation. # Scenario 2: Path traversal via symlinks or relative paths target_path = os.path.join(base_dir, user_controlled_filename) # Vulnerability: No check like 'os.path.abspath(target_path).startswith(os.path.abspath(base_dir))' # after resolving symlinks (os.path.realpath). print(f"[*] Attempting to write to: {os.path.realpath(target_path)}") with open(target_path, 'w') as f: f.write(content) print("[+] Write operation completed.") # Exploit Example # Attacker uses delegated signing authority to specify a malicious target. # Using '../' to escape the intended directory. malicious_payload = "../../../tmp/pwned_by_cve_2026_6968.txt" vulnerable_write("/var/tough/repository", malicious_payload, "EXPLOITED")

{"cve": {"id": "CVE-2026-6968", "sourceIdentifier": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "published": "2026-04-24T20:16:29.170", "lastModified": "2026-05-06T15:36:48.853", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Incomplete path traversal fixes in awslabs/tough before tough-v0.22.0 allow remote authenticated users with delegated signing authority to write files outside intended output directories via absolute target names in copy_target/link_target, symlinked parent directories in save_target, or symlinked metadata filenames in SignedRole::write, because write paths trust the joined destination path without post-resolution containment verification.\n\nWe recommend you upgrade to tough-v0.22.0 / tuftool-v0.15.0."}], "metrics": {"cvssMetricV40": [{"source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:L/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": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "HIGH", "subAvailabilityImpact": "LOW", "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": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L", "baseScore": 5.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.6, "impactScore": 4.2}, {"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:H/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-22"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:amazon:tough:*:*:*:*:*:rust:*:*", "versionStartIncluding": "0.9.0", "versionEndExcluding": "0.22.0", "matchCriteriaId": "51AC1B2A-ACBA-4ABE-9A31-1132436EEF0F"}, {"vulnerable": true, "criteria": "cpe:2.3:a:amazon:tuftool:*:*:*:*:*:rust:*:*", "versionEndExcluding": "0.15.0", "matchCriteriaId": "E83215AA-4B4B-44C1-A062-B7212CF33EF5"}]}]}], "references": [{"url": "https://aws.amazon.com/security/security-bulletins/2026-019-aws/", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Vendor Advisory"]}, {"url": "https://crates.io/crates/tough/0.22.0", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Product"]}, {"url": "https://crates.io/crates/tuftool/0.15.0", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Product"]}, {"url": "https://github.com/awslabs/tough/releases/tag/tough-v0.22.0", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Release Notes"]}, {"url": "https://github.com/awslabs/tough/releases/tag/tuftool-v0.15.0", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Release Notes"]}, {"url": "https://github.com/awslabs/tough/security/advisories/GHSA-v57p-gppj-p9vg", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Vendor Advisory"]}]}}