CVE-2026-33376

Description

When using an IPv6 allow-list for the Auth Proxy feature, it defaults to /32 addresses. Addresses specifying a mask explicitly are not affected; to mitigate easily, add the desired mask (usually /128) to the addresses. Only auth proxy is affected; Okta, SAML, LDAP, etc are unaffected here.

CVSS Details

CVSS Score

7.4

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Grafana (具体受影响版本未在提供文本中明确列出，请参考官方通告)

PoC / Exploit Code

⚠ For Security Research Only

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

python

#!/usr/bin/env python3
# PoC for CVE-2026-33376: Grafana IPv6 Auth Proxy Misconfiguration
# This script demonstrates how a loose /32 mask allows unauthorized IPs.

import ipaddress

def check_bypass(target_ipv6_config, attacker_ip):
    """
    Simulates the vulnerable logic where unspecified masks default to /32.
    """
    # Vulnerable logic: if no mask is provided, assume /32
    if '/' not in target_ipv6_config:
        vulnerable_network = ipaddress.IPv6Network(f"{target_ipv6_config}/32", strict=False)
        print(f"[VULNERABLE] Config '{target_ipv6_config}' interpreted as {vulnerable_network}")
    else:
        vulnerable_network = ipaddress.IPv6Network(target_ipv6_config, strict=False)
        print(f"[SAFE] Config '{target_ipv6_config}' interpreted as {vulnerable_network}")

    attacker = ipaddress.IPv6Address(attacker_ip)
    
    if attacker in vulnerable_network:
        return f"[SUCCESS] Attacker IP {attacker} is ALLOWED by the vulnerable config."
    else:
        return f"[FAIL] Attacker IP {attacker} is BLOCKED."

if __name__ == "__main__":
    # Scenario: Admin allows a specific IPv6 address but forgets the mask
    admin_allowed_ip = "2001:0db8:85a3:0000:0000:8a2e:0370:7334"
    
    # Attacker generates a different IP within the same /32 scope
    attacker_generated_ip = "2001:0db8:ffff:ffff:ffff:ffff:ffff:ffff"
    
    print(f"Testing bypass from {attacker_generated_ip} against config {admin_allowed_ip}...")
    print(check_bypass(admin_allowed_ip, attacker_generated_ip))

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-33376
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-33376
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-33376/
[4] VulDB https://vuldb.com/cve/CVE-2026-33376
[5] https://grafana.com/security/security-advisories/cve-2026-33376

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-33376", "sourceIdentifier": "[email protected]", "published": "2026-05-13T20:16:20.367", "lastModified": "2026-05-14T16:21:02.930", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "When using an IPv6 allow-list for the Auth Proxy feature, it defaults to /32 addresses. Addresses specifying a mask explicitly are not affected; to mitigate easily, add the desired mask (usually /128) to the addresses. Only auth proxy is affected; Okta, SAML, LDAP, etc are unaffected here."}], "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:H/I:H/A:N", "baseScore": 7.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 5.2}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-1188"}]}], "references": [{"url": "https://grafana.com/security/security-advisories/cve-2026-33376", "source": "[email protected]"}]}}