Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
JupyterHub versions before 5.5.0 are vulnerable to unauthenticated denial of service. Invalid input submitted to the login form causes unbounded logging output, and this affects only form-based authenticators such as the default PAM authenticator. Upgrade to JupyterHub 5.5.0 or later; if upgrading is not possible, switch to an authenticator that does not use a login form, such as OAuthenticator.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 5.3 | Medium | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0044, the 38th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:09 UTC First seen by agentprime
- 31 Oct 2026, 14:09 UTC Confirmed by OSV