{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-40556", "assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6", "state": "PUBLISHED", "assignerShortName": "CERT-PL", "dateReserved": "2026-04-14T09:44:32.553Z", "datePublished": "2026-04-28T13:54:11.918Z", "dateUpdated": "2026-04-28T14:28:55.143Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "nano", "repo": "https://cgit.git.savannah.gnu.org/cgit/nano.git/", "vendor": "GNU", "versions": [{"lessThan": "9.0", "status": "affected", "version": "2.9.1", "versionType": "semver"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Environments where the process umask does not sufficiently restrict permissions<br>"}], "value": "Environments where the process umask does not sufficiently restrict permissions"}], "credits": [{"lang": "en", "type": "finder", "value": "Michal Majchrowicz (AFINE)"}, {"lang": "en", "type": "finder", "value": "Marcin Wyczechowski (AFINE)"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "GNU nano creates the user\u2019s ~/.local directory with overly permissive permissions when the directory does not exist yet. On first use of features requiring Cross-Desktop Group (XDG) data storage, nano explicitly requests directory mode 0777, making the directory world\u2011writable in environments where the process umask does not sufficiently restrict permissions.<br>In systems with a relaxed or zero umask, such as container environments, CI/CD runners, embedded systems, or user shells configured with umask 000, this results in ~/.local being created as world\u2011writable. A local attacker can exploit a race window between nano\u2019s creation of ~/.local and its subsequent creation of more restrictive subdirectories to write attacker\u2011controlled files into the victim\u2019s XDG directory hierarchy.<br><br>This problem was fixed in nano version 9.0"}], "value": "GNU nano creates the user\u2019s ~/.local directory with overly permissive permissions when the directory does not exist yet. On first use of features requiring Cross-Desktop Group (XDG) data storage, nano explicitly requests directory mode 0777, making the directory world\u2011writable in environments where the process umask does not sufficiently restrict permissions.\nIn systems with a relaxed or zero umask, such as container environments, CI/CD runners, embedded systems, or user shells configured with umask 000, this results in ~/.local being created as world\u2011writable. A local attacker can exploit a race window between nano\u2019s creation of ~/.local and its subsequent creation of more restrictive subdirectories to write attacker\u2011controlled files into the victim\u2019s XDG directory hierarchy.\n\nThis problem was fixed in nano version 9.0"}], "impacts": [{"capecId": "CAPEC-122", "descriptions": [{"lang": "en", "value": "CAPEC-122: Privilege Abuse"}]}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "LOCAL", "baseScore": 2.1, "baseSeverity": "LOW", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-732", "description": "CWE-732: Incorrect Permission Assignment for Critical Resource", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6", "shortName": "CERT-PL", "dateUpdated": "2026-04-28T13:54:11.918Z"}, "references": [{"tags": ["third-party-advisory"], "url": "https://cert.pl/en/posts/2026/04/CVE-2026-40556/"}, {"tags": ["product"], "url": "https://www.nano-editor.org/"}, {"tags": ["patch"], "url": "https://cgit.git.savannah.gnu.org/cgit/nano.git/commit/?id=cb43493e"}], "source": {"discovery": "EXTERNAL"}, "tags": ["x_open-source"], "title": "Insecure Directory Permissions in GNU nano Leading to Privilege Abuse", "x_generator": {"engine": "Vulnogram 0.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-04-28T14:28:37.470889Z", "id": "CVE-2026-40556", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-28T14:28:55.143Z"}}]}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "GNU nano creates the user\u2019s ~/.local directory with overly permissive permissions when the directory does not exist yet. On first use of features requiring Cross-Desktop Group (XDG) data storage, nano explicitly requests directory mode 0777, making the directory world\u2011writable in environments where the process umask does not sufficiently restrict permissions.\nIn systems with a relaxed or zero umask, such as container environments, CI/CD runners, embedded systems, or user shells configured with umask 000, this results in ~/.local being created as world\u2011writable. A local attacker can exploit a race window between nano\u2019s creation of ~/.local and its subsequent creation of more restrictive subdirectories to write attacker\u2011controlled files into the victim\u2019s XDG directory hierarchy.\n\nThis problem was fixed in nano version 9.0"}], "id": "CVE-2026-40556", "lastModified": "2026-04-28T15:16:30.150", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "LOCAL", "availabilityRequirement": "NOT_DEFINED", "baseScore": 2.1, "baseSeverity": "LOW", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "cvd@cert.pl", "type": "Secondary"}]}, "published": "2026-04-28T15:16:30.150", "references": [{"source": "cvd@cert.pl", "url": "https://cert.pl/en/posts/2026/04/CVE-2026-40556/"}, {"source": "cvd@cert.pl", "url": "https://cgit.git.savannah.gnu.org/cgit/nano.git/commit/?id=cb43493e"}, {"source": "cvd@cert.pl", "url": "https://www.nano-editor.org/"}], "sourceIdentifier": "cvd@cert.pl", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-732"}], "source": "cvd@cert.pl", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.9.1,9.0)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "nano", "source": "cna", "vendor": "GNU"}, "product": "nano", "vendor": "gnu"}], "created": "2026-04-28T16:00:12.302186+00:00", "updated": "2026-04-28T16:00:12.302286+00:00", "vendors": ["gnu", "gnu$PRODUCT$nano"]}