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LTI JupyterHub Authenticator: Unbounded Memory Growth via Nonce Storage (Denial of Service)

Moderate severity GitHub Reviewed Published Apr 2, 2026 in jupyterhub/ltiauthenticator • Updated Apr 6, 2026

Package

pip jupyterhub-ltiauthenticator (pip)

Affected versions

<= 1.6.2

Patched versions

1.6.3

Description

Summary

The LTI 1.1 validator stores OAuth nonces in a class-level dictionary that grows without bounds. Nonces are added before signature validation, so an attacker with knowledge of a valid consumer key can send repeated requests with unique nonces to gradually exhaust server memory, causing a denial of service.

Patches

  • upgrade jupyterhub-litauthenticator to 1.6.3

References

@minrk minrk published to jupyterhub/ltiauthenticator Apr 2, 2026
Published to the GitHub Advisory Database Apr 3, 2026
Reviewed Apr 3, 2026
Published by the National Vulnerability Database Apr 3, 2026
Last updated Apr 6, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(6th percentile)

Weaknesses

Missing Release of Memory after Effective Lifetime

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse. Learn more on MITRE.

Allocation of Resources Without Limits or Throttling

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. Learn more on MITRE.

CVE ID

CVE-2026-34052

GHSA ID

GHSA-8mxq-7xr7-2fxj

Source code

Credits

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