CVE-2026-33376Network attack vector

Authentication bypass via overbroad IPv6 allow-list defaults

Published May 13, 2026 · Updated May 13, 2026

Authentication bypass in Grafana OSS 9.4.0 through 13.0.1 allows remote attackers to spoof Auth Proxy identities from overbroad IPv6 ranges. The Auth Proxy IPv6 allow-list handling assigns an address without an explicit prefix length a /32 network instead of a host-sized /128, trusting unintended source addresses. Exploitation requires Auth Proxy to be enabled with an unmasked IPv6 whitelist entry; other authentication providers are unaffected, and successful requests obtain the spoofed identity's access.

CVSS severity7.4
High
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Authentication bypass in Grafana OSS 9.4.0 through 13.0.1 allows remote attackers to spoof Auth Proxy identities from overbroad IPv6 ranges. The Auth Proxy IPv6 allow-list handling assigns an address without an explicit prefix length a /32 network instead of a host-sized /128, trusting unintended source addresses. Exploitation requires Auth Proxy to be enabled with an unmasked IPv6 whitelist entry; other authentication providers are unaffected, and successful requests obtain the spoofed identity's access.

The record

CVE
CVE-2026-33376
Published
May 13, 2026
Updated
May 13, 2026
Vendor
Grafana Labs
Product
Grafana OSS
Classifications
CWE-1188, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=11.6.14 <11.6.14+security-04
  2. Affected versionversion=12.0.0 <=12.2.8
  3. Affected versionversion=12.2.8 <12.2.8+security-04
  4. Affected versionversion=12.3.0 <=12.3.6
  5. Affected versionversion=12.3.6 <12.3.6+security-04
  6. Affected versionversion=12.4.0 <=12.4.3
  7. Affected versionversion=12.4.3 <12.4.3+security-02
  8. Affected versionversion=13.0.0 <=13.0.1
  9. Affected versionversion=13.0.1 <13.0.1+security-01
  10. Affected versionversion=9.4.0 <=11.6.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Grafana Labs · Grafana OSSversion=11.6.14 <11.6.14+security-04; version=12.0.0 <=12.2.8; version=12.2.8 <12.2.8+security-04; version=12.3.0 <=12.3.6; version=12.3.6 <12.3.6+security-04; version=12.4.0 <=12.4.3; version=12.4.3 <12.4.3+security-02; version=13.0.0 <=13.0.1; version=13.0.1 <13.0.1+security-01; version=9.4.0 <=11.6.14

Published CVSS scores

7.4Grafana LabsCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1188Initialization of a Resource with an Insecure Default
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo