Vulnerability-Lookup

GHSA-P43P-WHWX-Q52H

Vulnerability from github – Published: 2026-08-25 19:29 – Updated: 2026-08-25 19:29

Summary

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

Details

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.

Severity

5.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "jupyterhub"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.5.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54338"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-25T19:29:19Z",
    "nvd_published_at": "2026-08-07T21:17:29Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nInvalid 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.\n\n### Patches\n\nUpgrade to 5.5.0.\n\n### Workarounds\n\nUse an Authenticator that doesn\u0027t use a login form, such as OAuthenticator.",
  "id": "GHSA-p43p-whwx-q52h",
  "modified": "2026-08-25T19:29:19Z",
  "published": "2026-08-25T19:29:19Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54338"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/jupyterhub/jupyterhub"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login"
}

CVE-2026-54338 (GCVE-0-2026-54338)

Vulnerability from cvelistv5 – Published: 2026-08-07 20:52 – Updated: 2026-08-11 01:15

Title

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

Summary

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.

Severity

5.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-11 01:15 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/jupyterhub/jupyterhub/security…	x_refsource_CONFIRM
https://github.com/jupyterhub/jupyterhub/commit/d…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
jupyterhub	jupyterhub	Affected: < 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.

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-54338",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-11T01:15:40.394275Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-11T01:15:53.601Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "jupyterhub",
          "vendor": "jupyterhub",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 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."
            }
          ]
        }
      ],
      "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."
        }
      ],
      "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",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-07T20:52:55.068Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h"
        },
        {
          "name": "https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a"
        }
      ],
      "source": {
        "advisory": "GHSA-p43p-whwx-q52h",
        "discovery": "UNKNOWN"
      },
      "title": "JupyterHub: Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-54338",
    "datePublished": "2026-08-07T20:52:55.068Z",
    "dateReserved": "2026-06-12T19:23:22.316Z",
    "dateUpdated": "2026-08-11T01:15:53.601Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.