CVE-2026-34052: LTI JupyterHub Authenticator Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-8mxq-7xr7-2fxj
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CVSS 5.9
CWE-770 CWE-401
Published
Advisory Summary

CVE-2026-34052 is a MODERATE (CVSS 5.9) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting LTI JupyterHub Authenticator libraries in the PyPI ecosystem. The issue involves unbounded memory growth via nonce storage (denial of service). Remediation is available by upgrading affected packages to version 1.6.3.

CVE-2026-34052 at a Glance

CVE Identifier CVE-2026-34052
GHSA Identifier GHSA-8mxq-7xr7-2fxj
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product LTI JupyterHub Authenticator
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-34052

To remediate this vulnerability, upgrade all affected LTI JupyterHub Authenticator dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

jupyterhub-ltiauthenticator fixed: 1.6.3 
pip install jupyterhub-ltiauthenticator>=1.6.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show jupyterhub-ltiauthenticator

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-34052, inspect your installed packages using pip:

pip show jupyterhub-ltiauthenticator

Analyze the terminal output to locate any version of LTI JupyterHub Authenticator in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.6.3), your application is affected.

Note: The pip show jupyterhub-ltiauthenticator command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where 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. In LTI JupyterHub Authenticator, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## 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

CVE-2026-34052 Affected LTI JupyterHub Authenticator Versions

1 component(s)
Fixed Versions:
1.6.3
Product / Package Ecosystem Affected Versions Fixed Version
jupyterhub-ltiauthenticator
pypi/jupyterhub-ltiauthenticator
PyPI
< 1.6.3
1.6.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/jupyterhub/ltiauthenticator/security/advisories/GHSA-8mxq-7xr7-2fxj
NVD — CVE-2026-34052 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34052
LTI JupyterHub Authenticator Source Repository REPOSITORY
https://github.com/jupyterhub/ltiauthenticator
LTI JupyterHub Authenticator Release RELEASE
https://github.com/jupyterhub/ltiauthenticator/releases/tag/1.6.3

Frequently Asked Questions

What is CVE-2026-34052?
CVE-2026-34052 is a security vulnerability in LTI JupyterHub Authenticator involving Unbounded Memory Growth via Nonce Storage (Denial of Service) under CWE-770: Allocation of Resources Without Limits or Throttling.
Which LTI JupyterHub Authenticator versions are affected?
Affected versions include releases prior to 1.6.3 across affected packages: jupyterhub-ltiauthenticator.
What version fixes CVE-2026-34052?
Upgrading to 1.6.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is jupyterhub-ltiauthenticator affected?
Yes, jupyterhub-ltiauthenticator is affected in releases prior to 1.6.3. Upgrade your dependency to 1.6.3 or later.
What is the CVSS score of CVE-2026-34052?
CVE-2026-34052 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-34052?
CVE-2026-34052 is classified under CWE-770: 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.).
How can I check PyPI dependencies for CVE-2026-34052?
Run the dependency tree command: 'pip show jupyterhub-ltiauthenticator'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8mxq-7xr7-2fxj",
  "modified" : "2026-04-06T23:10:01Z",
  "published" : "2026-04-03T21:42:35Z",
  "aliases" : [ "CVE-2026-34052" ],
  "summary" : "LTI JupyterHub Authenticator: Unbounded Memory Growth via Nonce Storage (Denial of Service)",
  "details" : "## Summary\n\nThe 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.\n\n## Patches\n\n- upgrade jupyterhub-litauthenticator to 1.6.3",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "jupyterhub-ltiauthenticator"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.6.3"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.6.2"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/jupyterhub/ltiauthenticator/security/advisories/GHSA-8mxq-7xr7-2fxj"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34052"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jupyterhub/ltiauthenticator"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jupyterhub/ltiauthenticator/releases/tag/1.6.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-401", "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-03T21:42:35Z",
    "nvd_published_at" : "2026-04-03T23:17:03Z"
  }
}