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Not in CISA KEV
MEDIUM severity

GHSA-p43p-whwx-q52h

MEDIUMFix: jupyterhub/jupyterhub@d6dc595

GHSA-p43p-whwx-q52h is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in jupyterhub. O3 Security confirms whether GHSA-p43p-whwx-q52h is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login

Also known asCVE-2026-54338
Published
Aug 25, 2026
Updated
Aug 26, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Aug 26, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
🐍jupyterhub

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

Invalid input to login resulted in unbounded logging output. Only form-based Authenticators (the default PAM Authenticator, but not the more widely used OAuthenticator) are affected.

Patches

Upgrade to 5.5.0.

Workarounds

Use an Authenticator that doesn't use a login form, such as OAuthenticator.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIjupyterhuball versions5.5.0

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyterhub. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update jupyterhub to 5.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-p43p-whwx-q52h is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-p43p-whwx-q52h is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-p43p-whwx-q52h. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact Invalid input to login resulted in unbounded logging output. Only form-based Authenticators (the default PAM Authenticator, but not the more widely used OAuthenticator) are affected. ### Patches Upgrade to 5.5.0. ### Workarounds Use an Authenticator that doesn't use a login form, such as OAuthenticator.
O3 Security · Impact-Aware SCA

Is GHSA-p43p-whwx-q52h in your dependencies?

O3 detects GHSA-p43p-whwx-q52h across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

GHSA-p43p-whwx-q52h: jupyterhub (Medium… | O3 Security