{"id":"CVE-2026-27807","state":"PUBLISHED","title":"MarkUs: YAML alias (‘billion laughs’) DoS in config upload","description":"MarkUs is a web application for the submission and grading of student assignments. Prior to version 2.9.4, MarkUs allows course instructors to upload YAML files to create/update various entities (e.g., assignment settings). These YAML files are parsed with aliases enabled. This issue has been patched in version 2.9.4.","publishedAt":"2026-03-06T02:48:28.384Z","updatedAt":"2026-03-06T16:10:43.887Z","severity":{"score":4.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["MarkUsProject Markus"],"affected":[{"vendor":"MarkUsProject","product":"Markus","versions":[{"version":"< 2.9.4","status":"affected"}]}],"references":["https://github.com/MarkUsProject/Markus/security/advisories/GHSA-m9rx-85mx-q9h6","https://github.com/MarkUsProject/Markus/releases/tag/v2.9.4"],"weaknesses":["CWE-776"],"ingestedAt":"2026-10-29T20:11:31.369Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/27xxx/CVE-2026-27807.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-27807","state":"PUBLISHED","datePublished":"2026-03-06T02:48:28.384Z","dateUpdated":"2026-03-06T16:10:43.887Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-02-24T02:31:33.267Z"},"containers":{"cna":{"title":"MarkUs: YAML alias (‘billion laughs’) DoS in config upload","descriptions":[{"lang":"en","value":"MarkUs is a web application for the submission and grading of student assignments. Prior to version 2.9.4, MarkUs allows course instructors to upload YAML files to create/update various entities (e.g., assignment settings). These YAML files are parsed with aliases enabled. This issue has been patched in version 2.9.4."}],"affected":[{"vendor":"MarkUsProject","product":"Markus","versions":[{"version":"< 2.9.4","status":"affected"}]}],"references":[{"url":"https://github.com/MarkUsProject/Markus/security/advisories/GHSA-m9rx-85mx-q9h6","name":"https://github.com/MarkUsProject/Markus/security/advisories/GHSA-m9rx-85mx-q9h6","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/MarkUsProject/Markus/releases/tag/v2.9.4","name":"https://github.com/MarkUsProject/Markus/releases/tag/v2.9.4","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":4.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"HIGH","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-776","lang":"en","description":"CWE-776: Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-03-06T02:48:28.384Z"},"source":{"advisory":"GHSA-m9rx-85mx-q9h6","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-06T15:50:49.801664Z","id":"CVE-2026-27807","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-03-06T16:10:43.887Z"}}]}}}