p PatchFirst

CVE-2026-54338

CVE-2026-54338 · JupyterHub: Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 5.3 · Medium · EPSS 0.4% · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • jupyterhub

    Versions
    • < 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.: Affected

    No fix published

  • jupyterhub Debian:12

    Versions
    • 3.0.0+ds1-1
    • 5.0.0+ds1-1
    • 5.0.0+ds1-2
    • 5.0.0+ds1-3
    • 5.0.0+ds1-4
    • 5.2.1+ds1-1
    • 5.2.1+ds1-2
    • 5.2.1+ds1-3
    • 5.2.1+ds1-4
    • 5.2.1+ds1-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • jupyterhub Debian:13

    Versions
    • 5.2.1+ds1-4
    • 5.2.1+ds1-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • jupyterhub Debian:14

    Versions
    • 5.2.1+ds1-4
    • 5.2.1+ds1-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • jupyterhub PyPI

    Versions
    • 0.1.0
    • 0.2.0
    • 0.3.0
    • 0.4.0
    • 0.4.1
    • 0.5.0
    • 0.6.0
    • 0.6.1
    • 0.7.0
    • 0.7.0b1
    • 0.7.1
    • 0.7.2
    • 0.8.0
    • 0.8.0b1
    • 0.8.0b2
    • 0.8.0b3
    • 0.8.0b4
    • 0.8.0b5
    • 0.8.0rc1
    • 0.8.0rc2
    • 0.8.1
    • 0.9.0
    • 0.9.0b1
    • 0.9.0b2
    • 0.9.0b3
    • 0.9.0rc1
    • 0.9.1
    • 0.9.2
    • 0.9.3
    • 0.9.4
    • 0.9.5
    • 0.9.6
    • 1.0.0
    • 1.0.0b1
    • 1.0.0b2
    • 1.1.0
    • 1.1.0b1
    • 1.2.0
    • 1.2.0b1
    • 1.2.1
    • 1.2.2
    • 1.3.0
    • 1.4.0
    • 1.4.1
    • 1.4.2
    • 1.5.0
    • 1.5.1
    • 2.0.0
    • 2.0.0b1
    • 2.0.0b2
    • 2.0.0b3
    • 2.0.0rc1
    • 2.0.0rc2
    • 2.0.0rc3
    • 2.0.0rc4
    • 2.0.0rc5
    • 2.0.1
    • 2.0.2
    • 2.1.0
    • 2.1.1
    • 2.2.0
    • 2.2.1
    • 2.2.2
    • 2.3.0
    • 2.3.1
    • 3.0.0
    • 3.0.0b1
    • 3.1.0
    • 3.1.1
    • 4.0.0
    • 4.0.0b1
    • 4.0.0b2
    • 4.0.1
    • 4.0.2
    • 4.1.0
    • 4.1.1
    • 4.1.2
    • 4.1.3
    • 4.1.4
    • 4.1.5
    • 4.1.6
    • 5.0.0
    • 5.0.0b1
    • 5.0.0b2
    • 5.1.0
    • 5.2.0
    • 5.2.1
    • 5.3.0
    • 5.3.0rc0
    • 5.4.0
    • 5.4.1
    • 5.4.2
    • 5.4.3
    • 5.4.4
    • 5.4.5
    • 5.4.6
    Affected ranges
    • ECOSYSTEM: < 5.5.0

    Update to 5.5.0

  • jupyterhub Ubuntu:22.04:LTS

    Versions
    • 2.0.0+ds1-1
    • 2.0.0+ds1-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • jupyterhub Ubuntu:24.04:LTS

    Versions
    • 3.0.0+ds1-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • jupyterhub Ubuntu:26.10

    Versions
    • 5.2.1+ds1-4
    • 5.2.1+ds1-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • jupyterhub Ubuntu:26.04:LTS

    Versions
    • 5.2.1+ds1-4
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

Check your server →