{"api_version":"1","generated_at":"2026-11-10T10:52:08+00:00","cve":"CVE-2026-124683","urls":{"html":"https://cve.report/CVE-2026-124683","api":"https://cve.report/api/cve/CVE-2026-124683.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-124683","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-124683"},"summary":{"title":"CVE-2026-124683","description":"Eclipse Langium versions 3.2.0 through 4.4.0 contain an inefficient algorithmic complexity issue (CWE-407) in the opt-in IndentationAwareTokenBuilder and IndentationAwareLexer. When producing DEDENT tokens, the token builder recomputes line numbers by re-scanning the entire preceding document text. A document whose indentation changes on most lines then takes quadratic time to tokenize. Because tokenization is synchronous, a crafted document of a few hundred kilobytes can block the Node.js event loop for tens of seconds. That causes a DoS for every user served by the same process. Languages built with the DefaultLexer and DefaultTokenBuilder are unaffected.","state":"PUBLISHED","assigner":"eclipse","published_at":"2026-11-09 17:17:27","updated_at":"2026-11-09 17:17:27"},"problem_types":["CWE-407","CWE-407 CWE-407"],"metrics":[{"version":"4.0","source":"emo@eclipse.org","type":"Secondary","score":"8.7","severity":"HIGH","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/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","data":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/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":8.7,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","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"}},{"version":"4.0","source":"CNA","type":"CVSS","score":"8.7","severity":"HIGH","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","data":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"}}],"references":[{"url":"https://gitlab.eclipse.org/security/cve-assignment/-/work_items/553","name":"https://gitlab.eclipse.org/security/cve-assignment/-/work_items/553","refsource":"emo@eclipse.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/1069","name":"https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/1069","refsource":"emo@eclipse.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/eclipse-langium/langium/security/advisories/GHSA-297v-g8mm-qj4h","name":"https://github.com/eclipse-langium/langium/security/advisories/GHSA-297v-g8mm-qj4h","refsource":"emo@eclipse.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-124683","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-124683","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Eclipse Foundation","product":"Eclipse Langium","version":"affected 3.2.0 4.4.0 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"https://github.com/blackrose-0xday","lang":"en"}],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-124683","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-11-09T16:47:35.260234Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-11-09T16:47:45.873Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Eclipse Langium","vendor":"Eclipse Foundation","versions":[{"lessThanOrEqual":"4.4.0","status":"affected","version":"3.2.0","versionType":"semver"}]}],"credits":[{"lang":"en","type":"finder","value":"https://github.com/blackrose-0xday"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>Eclipse Langium versions 3.2.0 through 4.4.0 contain an inefficient algorithmic complexity issue (CWE-407) in the opt-in IndentationAwareTokenBuilder and IndentationAwareLexer. When producing DEDENT tokens, the token builder recomputes line numbers by re-scanning the entire preceding document text. A document whose indentation changes on most lines then takes quadratic time to tokenize. Because tokenization is synchronous, a crafted document of a few hundred kilobytes can block the Node.js event loop for tens of seconds. That causes a DoS for every user served by the same process. Languages built with the DefaultLexer and DefaultTokenBuilder are unaffected.</p>"}],"value":"Eclipse Langium versions 3.2.0 through 4.4.0 contain an inefficient algorithmic complexity issue (CWE-407) in the opt-in IndentationAwareTokenBuilder and IndentationAwareLexer. When producing DEDENT tokens, the token builder recomputes line numbers by re-scanning the entire preceding document text. A document whose indentation changes on most lines then takes quadratic time to tokenize. Because tokenization is synchronous, a crafted document of a few hundred kilobytes can block the Node.js event loop for tens of seconds. That causes a DoS for every user served by the same process. Languages built with the DefaultLexer and DefaultTokenBuilder are unaffected."}],"impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130"}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","description":"CWE-407","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-11-09T16:02:50.370Z","orgId":"e51fbebd-6053-4e49-959f-1b94eeb69a2c","shortName":"eclipse"},"references":[{"url":"https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/1069"},{"url":"https://github.com/eclipse-langium/langium/security/advisories/GHSA-297v-g8mm-qj4h"},{"url":"https://gitlab.eclipse.org/security/cve-assignment/-/work_items/553"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 1.0.5"}}},"cveMetadata":{"assignerOrgId":"e51fbebd-6053-4e49-959f-1b94eeb69a2c","assignerShortName":"eclipse","cveId":"CVE-2026-124683","datePublished":"2026-11-09T16:02:50.370Z","dateReserved":"2026-11-09T10:36:46.112Z","dateUpdated":"2026-11-09T16:47:45.873Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-11-09 17:17:27","lastModifiedDate":"2026-11-09 17:17:27","problem_types":["CWE-407","CWE-407 CWE-407"],"metrics":{"cvssMetricV40":[{"source":"emo@eclipse.org","type":"Secondary","cvssData":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/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":8.7,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","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"}}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-11-09T16:47:35.260234Z","id":"CVE-2026-124683","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"124683","Ordinal":"1","Title":"CVE-2026-124683","CVE":"CVE-2026-124683","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"124683","Ordinal":"1","NoteData":"Eclipse Langium versions 3.2.0 through 4.4.0 contain an inefficient algorithmic complexity issue (CWE-407) in the opt-in IndentationAwareTokenBuilder and IndentationAwareLexer. When producing DEDENT tokens, the token builder recomputes line numbers by re-scanning the entire preceding document text. A document whose indentation changes on most lines then takes quadratic time to tokenize. Because tokenization is synchronous, a crafted document of a few hundred kilobytes can block the Node.js event loop for tens of seconds. That causes a DoS for every user served by the same process. Languages built with the DefaultLexer and DefaultTokenBuilder are unaffected.","Type":"Description","Title":"CVE-2026-124683"}]}}}