{"cve":"CVE-2026-54338","nvd":{"published":"2026-08-07T21:17:29.017","modified":"2026-09-09T20:58:37.713","status":"Awaiting Analysis","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-400"],"references":["https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a","https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:47:54.990491175+00:00"},"epss":{"cve":"CVE-2026-54338","score":0.00437,"percentile":0.37977,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-p43p-whwx-q52h","url":"https://osv.dev/vulnerability/GHSA-p43p-whwx-q52h","summary":"JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login","modified":"2026-09-29T10:10:48.091771976Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub","purl":"pkg:pypi/jupyterhub","ranges":["<5.5.0"],"fixed":["5.5.0"]}]},{"id":"PYSEC-2026-3853","url":"https://osv.dev/vulnerability/PYSEC-2026-3853","summary":"JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login","modified":"2026-09-29T10:10:48.091771976Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub","purl":"pkg:pypi/jupyterhub","ranges":["<5.5.0"],"fixed":["5.5.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}