CVE-2026-63041 Overview
CVE-2026-63041 is an authorization bypass vulnerability in Apache APISIX affecting the attach-consumer-label plugin. The plugin fails to sanitize certain input values before using them in a security decision, allowing an authenticated attacker to escalate privileges or bypass authorization controls. The flaw is categorized as [CWE-807] Reliance on Untrusted Inputs in a Security Decision.
The vulnerability affects Apache APISIX versions 3.11.0 through 3.17.0. The Apache APISIX project has released version 3.18.0 to remediate the issue.
Critical Impact
An attacker with low-level authenticated access can send crafted values to the attach-consumer-label plugin to escalate privileges or bypass authorization boundaries within the API gateway.
Affected Products
- Apache APISIX 3.11.0 through 3.17.0
- Deployments using the attach-consumer-label plugin
- API gateway routes relying on consumer label-based authorization decisions
Discovery Timeline
- 2026-08-26 - CVE-2026-63041 published to NVD
- 2026-08-26 - Last updated in NVD database
Technical Details for CVE-2026-63041
Vulnerability Analysis
Apache APISIX is a cloud-native API gateway that routes and authorizes traffic between clients and upstream services. The attach-consumer-label plugin attaches metadata labels to authenticated consumers, and downstream plugins or routing logic consume those labels to make authorization decisions.
The plugin does not correctly sanitize certain input values before assigning them to consumer labels. Because the resulting labels drive security-sensitive routing and access checks, an authenticated attacker can supply crafted values that alter authorization outcomes. The result is privilege escalation or authorization bypass within the gateway's trust boundary.
The weakness maps to [CWE-807] Reliance on Untrusted Inputs in a Security Decision. Security controls that consume the tainted labels treat attacker-controlled data as if it were trusted metadata generated by the gateway.
Root Cause
The root cause is missing or incomplete input validation in the attach-consumer-label plugin. The plugin accepts values from the request context and forwards them into consumer label fields that participate in authorization logic. Because sanitisation is incomplete, a caller can influence security decisions that should depend only on trusted, gateway-derived data.
Attack Vector
Exploitation is network-based and requires low-privileged authenticated access to a route that invokes the attach-consumer-label plugin. The attacker submits requests containing crafted label values. Downstream authorization logic then consumes the manipulated labels and grants access, roles, or permissions the attacker should not hold. No user interaction is required.
For technical specifics, see the Apache Mailing List Thread and the OpenWall OSS Security Update.
Detection Methods for CVE-2026-63041
Indicators of Compromise
- Requests to routes configured with the attach-consumer-label plugin containing unexpected label characters, control characters, or delimiter injection patterns.
- Consumers whose effective labels differ from those defined in the APISIX admin configuration.
- Access log entries showing successful requests to protected upstreams from consumers that should not hold matching label-based permissions.
Detection Strategies
- Audit APISIX route and plugin configurations to enumerate every route referencing attach-consumer-label and correlate them with downstream authorization plugins.
- Compare observed consumer label values in runtime telemetry against the authoritative labels defined in the APISIX admin API.
- Alert on 2xx responses to sensitive upstream paths where the requesting consumer's static configuration should have produced a 401 or 403.
Monitoring Recommendations
- Forward APISIX access logs, error logs, and admin API change events to a centralized analytics platform for correlation and retention.
- Baseline normal label values per consumer and alert on deviations, especially values containing separators, whitespace, or encoded characters.
- Monitor the APISIX admin API for unauthorized configuration changes to plugin definitions and consumer objects.
How to Mitigate CVE-2026-63041
Immediate Actions Required
- Upgrade Apache APISIX to version 3.18.0 or later on all gateway nodes.
- Inventory routes that enable the attach-consumer-label plugin and treat their upstream services as in-scope for post-patch review.
- Rotate any credentials or tokens issued to consumers whose label state cannot be verified as untampered.
Patch Information
Apache APISIX version 3.18.0 fixes the input sanitisation flaw in the attach-consumer-label plugin. Operators running any release from 3.11.0 through 3.17.0 should upgrade. Confirm the fix in your deployment by verifying the running binary version and reviewing the changelog referenced in the Apache Mailing List Thread.
Workarounds
- Disable the attach-consumer-label plugin on affected routes until the upgrade to 3.18.0 is completed.
- Enforce authorization decisions using consumer identifiers or credential-derived attributes rather than plugin-attached labels.
- Restrict access to the APISIX data plane with network segmentation and require strong authentication on all routes to reduce the pool of accounts that can attempt exploitation.
# Verify the installed Apache APISIX version
apisix version
# Example: disable the vulnerable plugin globally by removing it from
# the enabled plugins list in conf/config.yaml, then reload APISIX
# plugins:
# - ... (keep required plugins)
# # - attach-consumer-label # disabled pending upgrade to 3.18.0
apisix reload
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
