dbcve.org
ApicastApplication · Redhat

CVE-2021-3523

HIGH · 7.5 CVSS v3.1 Published 2022-04-27
Fix available
A fix is available. Upgrade to 2.11.0 or later.
See remediation →
84/100
Remediation priority · High
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
A flaw was found in 3Scale APICast in versions prior to 2.11.0, where it incorrectly identified connections for reuse. This flaw allows an attacker to bypass security restrictions for an API request when hosting multiple APIs on the same IP address.

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

A connection reuse vulnerability in 3Scale APICast versions prior to 2.11.0 causes incorrect identification of connections when multiple APIs are hosted on the same IP address. This flaw allows an attacker to bypass security restrictions and potentially access unauthorized API backends by exploiting the flawed connection reuse mechanism.

MitigationUpgrade APICast to version 2.11.0 or later to remediate the connection identification flaw.

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
ApicastApplication
Affected:< 2.11.0

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
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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. Identify APICast installation
    Locate APICast deployment by checking for running containers (e.g., 'docker ps', 'kubectl get pods'), services, or processes named 'apicast' in your environment
    Affected if APICast is not found in the environment, this CVE does not apply
  2. Determine installed APICast version
    Check the APICast version via docker image tag, installed package version, API response from the admin portal, or configuration file metadata. Compare against the affected range (all versions prior to 2.11.0)
    Affected if The installed version is any version earlier than 2.11.0
  3. Verify multiple API backends on shared IP
    Review the 3Scale API gateway configuration or API proxy settings to determine if multiple API backends/services are configured to use the same IP address or hostname
    Affected if Multiple API backends are configured to share a single IP address - this is required for the connection reuse flaw to be exploitable
  4. Check connection pool reuse configuration
    Inspect the API gateway or proxy configuration files and runtime settings related to HTTP connection pooling and keep-alive behavior between upstream backends
    Affected if Connection reuse/keep-alive pooling is enabled between different API backends sharing an IP

The environment is affected if APICast version is below 2.11.0 AND multiple API backends are configured on the same IP address, enabling the flawed connection reuse mechanism to cause misidentification.

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 2.11.0 or later
Fixed in 2.11.0
Interim mitigation

Upgrade APICast to version 2.11.0 or later to remediate the connection identification flaw.

Recommended fix High confidence

2.11.0 or later

  1. 1. Identify the current APICast version by checking the deployment configuration or running 'apicast --version'
  2. 2. Review the APICast 2.11.0 release notes for any migration requirements or configuration changes
  3. 3. Backup the current APICast configuration, including environment variables, policy configurations, and any custom Lua policies
  4. 4. Upgrade APICast to version 2.11.0 or later by updating the container image tag, Helm chart version, or package manager installation
  5. 5. After upgrade, verify that connection handling works correctly by testing API requests, especially when multiple APIs are hosted on the same IP address
  6. 6. Confirm the fix is applied by checking that APICast now properly identifies connections for reuse and enforces security restrictions correctly

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

Fix this in Apicast Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2021-3523 in production — separate from our analysis above.

No notes yet

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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