{
"id": "GHSA-p43p-whwx-q52h",
"aliases": [
"CVE-2026-54338"
],
"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't use a login form, such as OAuthenticator.",
"summary": "JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login",
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "5.5.0"
}
]
}
],
"package": {
"name": "jupyterhub",
"ecosystem": "PyPI"
}
}
],
"modified": "2026-08-25T19:29:19Z",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
}
],
"published": "2026-08-25T19:29:19Z",
"references": [
{
"url": "https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h",
"type": "WEB"
},
{
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54338",
"type": "ADVISORY"
},
{
"url": "https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a",
"type": "WEB"
},
{
"url": "https://github.com/jupyterhub/jupyterhub",
"type": "PACKAGE"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-400"
],
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": "2026-08-07T21:17:29Z",
"github_reviewed_at": "2026-08-25T19:29:19Z"
}
}