dbcve.org
ApisixApplication · Apache

CVE-2026-39998

HIGH · 8.8 CVSS v3.1 Published 2026-06-19
Fix available
A fix is available. Upgrade to 3.17.0 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper Input Validation vulnerability in Apache APISIX. The attacker can take advantage of certain configuration in forward-auth plugin to spoof identity headers. This issue affects Apache APISIX: from 2.12.0 through 3.16.0. Users are recommended to upgrade to version 3.17.0, which fixes the issue.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Apache APISIX forward-auth plugin contains an improper input validation vulnerability (CVSS 8.8) that allows attackers to spoof identity headers by exploiting certain configurations. This affects versions 2.12.0 through 3.16.0, enabling authentication bypass in systems relying on forward-auth for identity verification.

MitigationUpgrade Apache APISIX to version 3.17.0 or later. Prior to upgrade, audit forward-auth plugin configurations to identify and document any settings that could be exploited for header spoofing.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
ApisixApplication
Affected:>= 2.12.0, < 3.17.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Apache APISIX installed version
    Run 'apisix version' or check the version file in the APISIX installation directory (typically /usr/local/apisix or /opt/apisix). Also check package manager if installed via apt/yum.
    Affected if Version is >= 2.12.0 and < 3.17.0
  2. Verify forward-auth plugin is enabled
    Check APISIX config.yaml for 'plugins' list and look for 'forward-auth'. Also search route/configuration files for any route using 'forward-auth' in the plugins section.
    Affected if forward-auth appears in enabled plugins or is referenced in any route configuration
  3. Inspect forward-auth plugin configuration settings
    Examine the forward-auth plugin configuration in your route or global rule definitions. Look for the 'upstream_headers' and 'downstream_headers' configuration options that specify which headers are passed from the auth service to the client or upstream.
    Affected if upstream_headers or downstream_headers are configured without strict allowlist validation or the configuration allows arbitrary header injection from the external auth service response
  4. Check for unsafe header handling patterns
    Review the forward-auth configuration for any settings that pass headers from the authentication endpoint directly to the client without sanitization, especially when the auth endpoint response is attacker-controllable.
    Affected if Plugin configuration allows passing of arbitrary headers from the external auth service response without explicit allowlist filtering

You are affected if APISIX version is between 2.12.0 and 3.16.0 inclusive AND the forward-auth plugin is enabled with vulnerable header forwarding configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.17.0 or later
Fixed in 3.17.0
Interim mitigation

Upgrade Apache APISIX to version 3.17.0 or later. Prior to upgrade, audit forward-auth plugin configurations to identify and document any settings that could be exploited for header spoofing.

Recommended fix High confidence

3.17.0

  1. 1. Back up your current Apache APISIX configuration files (apisix.yaml, apisix.conf.yaml, and any custom plugin configurations)
  2. 2. Stop the Apache APISIX service to prevent requests during upgrade
  3. 3. For package-based installations: use your package manager to upgrade to version 3.17.0 (e.g., apt update && apt install apisix=3.17.0 or yum upgrade apisix-3.17.0)
  4. 4. For source-based installations: download Apache APISIX 3.17.0 from the official Apache repository and rebuild/replace the binaries
  5. 5. Verify the upgrade was successful by checking the version (apisix version command)
  6. 6. Restore your configuration files from the backup if needed
  7. 7. Start the Apache APISIX service
  8. 8. Test the forward-auth plugin functionality to ensure identity headers are now properly validated
Caveat Review the Apache APISIX 3.17.0 release notes for any minor breaking changes between your current version and 3.17.0

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Apisix Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-39998 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-39998 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data