{"id":"CVE-2026-54338","state":"PUBLISHED","title":"JupyterHub: Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login","description":"JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. Prior to 5.5.0, invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and storage resources. This issue is fixed in version 5.5.0.","publishedAt":"2026-08-07T20:52:55.068Z","updatedAt":"2026-08-11T01:15:53.601Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["jupyterhub jupyterhub"],"affected":[{"vendor":"jupyterhub","product":"jupyterhub","versions":[{"version":"< 5.5.0JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. Prior to 5.5.0, invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and storage resources. This issue is fixed in version 5.5.0.","status":"affected"}]}],"references":["https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h","https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a"],"weaknesses":["CWE-400"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54338.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54338","state":"PUBLISHED","datePublished":"2026-08-07T20:52:55.068Z","dateUpdated":"2026-08-11T01:15:53.601Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-12T19:23:22.316Z"},"containers":{"cna":{"title":"JupyterHub: Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login","descriptions":[{"lang":"en","value":"JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. Prior to 5.5.0, invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and storage resources. This issue is fixed in version 5.5.0."}],"affected":[{"vendor":"jupyterhub","product":"jupyterhub","versions":[{"version":"< 5.5.0JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. Prior to 5.5.0, invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and storage resources. This issue is fixed in version 5.5.0.","status":"affected"}]}],"references":[{"url":"https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h","name":"https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a","name":"https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-07T20:52:55.068Z"},"source":{"advisory":"GHSA-p43p-whwx-q52h","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-11T01:15:40.394275Z","id":"CVE-2026-54338","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-11T01:15:53.601Z"}}]}}}