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ApisixApplication · Apache

CVE-2026-31908

CRITICAL · 9.1 CVSS v3.1 Published 2026-04-14
Fix available
A fix is available. Upgrade to 3.16.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
Header injection vulnerability in Apache APISIX. The attacker can take advantage of certain configuration in forward-auth plugin to inject malicious headers. This issue affects Apache APISIX: from 2.12.0 through 3.15.0. Users are recommended to upgrade to version 3.16.0, 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

Header injection vulnerability in Apache APISIX's forward-auth plugin allows attackers to inject malicious headers due to improper input validation in certain plugin configurations. This affects versions 2.12.0 through 3.15.0, potentially allowing attackers to manipulate HTTP responses or bypass security controls.

MitigationUpgrade to Apache APISIX version 3.16.0 or later which contains the fix. Until upgrade is possible, review and restrict forward-auth plugin configurations to minimize attack surface.

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, < 3.16.0

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

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 installed Apache APISIX version
    Run `apisix version` or check the version file in the APISIX installation directory (e.g., /usr/local/apisix/apisix/version or the version embedded in the binary)
    Affected if The version is 2.12.0 through 3.15.0 (inclusive)
  2. Verify forward-auth plugin is enabled
    Check the APISIX configuration file (config.yaml or apisix.yaml) for 'plugins' or 'plugin_list' and confirm 'forward-auth' appears in the enabled plugins list
    Affected if The forward-auth plugin is present in the enabled plugins list
  3. Identify routes using forward-auth
    Query the APISIX Admin API endpoint `/apisix/admin/routes` or check the etcd database directly to list all route configurations that include 'forward-auth' in their 'plugins' section
    Affected if Any route has the forward-auth plugin configured
  4. Inspect forward-auth plugin configuration for user-controlled headers
    Review the forward-auth plugin configuration for each route - specifically examine the 'uri', 'auth_headers', and any other header-related parameters to determine if they accept user-supplied or upstream-derived values without validation
    Affected if The forward-auth configuration uses dynamic values (variables, request parameters, or upstream response data) in header fields without sanitization

You are affected if your APISIX version is between 2.12.0 and 3.15.0 and you have the forward-auth plugin enabled with a configuration that passes user-controlled or dynamic values into HTTP headers.

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 3.16.0 or later
Fixed in 3.16.0
Interim mitigation

Upgrade to Apache APISIX version 3.16.0 or later which contains the fix. Until upgrade is possible, review and restrict forward-auth plugin configurations to minimize attack surface.

Recommended fix High confidence

3.16.0

  1. 1. Back up your current Apache APISIX configuration files and any custom plugins
  2. 2. Review the Apache APISIX upgrade guide for your current version to 3.16.0
  3. 3. Download Apache APISIX version 3.16.0 from the official Apache repository
  4. 4. Stop the running Apache APISIX instance
  5. 5. Install or upgrade to version 3.16.0 following the official installation documentation
  6. 6. Restore your configuration files from the backup
  7. 7. Start the upgraded Apache APISIX instance
  8. 8. Verify the forward-auth plugin is functioning correctly with the new version
Caveat Review the changelog between your current version and 3.16.0 for any breaking changes in configuration syntax or plugin behavior

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.

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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-2026-31908 in production — separate from our analysis above.

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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