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KylinApplication · Apache

CVE-2021-45457

HIGH · 7.5 CVSS v3.1 Published 2022-01-06
Fix available
A fix is available. Upgrade to 3.1.3 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
In Apache Kylin, Cross-origin requests with credentials are allowed to be sent from any origin. This issue affects Apache Kylin 2 version 2.6.6 and prior versions; Apache Kylin 3 version 3.1.2 and prior versions; Apache Kylin 4 version 4.0.0 and prior versions.

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 Kylin versions 2.6.6, 3.1.2, and 4.0.0 and prior have a CORS misconfiguration that allows cross-origin requests with credentials (such as session cookies) from any origin (Access-Control-Allow-Origin: * with Access-Control-Allow-Credentials: true). This enables malicious websites to make authenticated requests on behalf of users, potentially leading to unauthorized data access or actions.

MitigationConfigure the CORS policy to explicitly whitelist trusted origins rather than allowing any origin. In the web server or application configuration, set Access-Control-Allow-Origin to specific domains and ensure Access-Control-Allow-Credentials is only enabled for trusted origins.

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
KylinApplication
Affected:>= 2.0.0, <= 2.6.6>= 3.0.0, < 3.1.3= 4.0.0

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
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 if Apache Kylin is running
    Check for Kylin processes or web service endpoints (default port 7070). Look for kylin processes via 'ps aux | grep kylin' or check if port 7070 is listening.
    Affected if Apache Kylin is not installed or not running (not affected)
  2. Determine installed Kylin version
    Check the version file typically found in $KYLIN_HOME/version or the about page in the Kylin web UI. Alternatively, check the kylin.properties or kylin-version.conf file.
    Affected if Version is >= 2.0.0 and <= 2.6.6, OR >= 3.0.0 and < 3.1.3, OR = 4.0.0 (potentially affected)
  3. Inspect CORS configuration files
    Examine the web.xml file in $KYLIN_HOME/tomcat/webapps/kylin/WEB-INF/ and look for CORS filter configuration. Also check kylin.properties for any cors.* settings.
    Affected if Configuration shows Access-Control-Allow-Origin set to '*' and Access-Control-Allow-Credentials set to 'true' simultaneously (vulnerable)
  4. Test actual CORS headers from the server
    Send an HTTP OPTIONS request with an Origin header (e.g., 'Origin: http://evil.com') and 'Access-Control-Request-Credentials: true'. Use: curl -I -X OPTIONS -H 'Origin: http://evil.com' -H 'Access-Control-Request-Credentials: true' http://<kylin-host>:7070/kylin/api/
    Affected if Response includes 'Access-Control-Allow-Origin: *' AND 'Access-Control-Allow-Credentials: true' (vulnerable and affected)

A user is affected if they are running a vulnerable Kylin version (2.0.0-2.6.6, 3.0.0-<3.1.3, or 4.0.0) AND the server responds with wildcard origin (*) alongside credentials allowed, allowing any external site to make authenticated requests.

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 3.1.3 or later
Fixed in 3.1.3
Interim mitigation

Configure the CORS policy to explicitly whitelist trusted origins rather than allowing any origin. In the web server or application configuration, set Access-Control-Allow-Origin to specific domains and ensure Access-Control-Allow-Credentials is only enabled for trusted origins.

Recommended fix High confidence

Kylin 2.x -> 2.6.7+; Kylin 3.x -> 3.1.3+; Kylin 4.x -> 4.0.1+

  1. 1. Identify the current Apache Kylin version in use (2.x, 3.x, or 4.x)
  2. 2. For Kylin 2.x users: Upgrade to version 2.6.7 or later
  3. 3. For Kylin 3.x users: Upgrade to version 3.1.3 or later
  4. 4. For Kylin 4.x users: Upgrade to version 4.0.1 or later
  5. 5. After upgrade, verify CORS configuration restricts allowed origins appropriately
  6. 6. Test that legitimate cross-origin requests still function as expected
Caveat Review release notes for any configuration or API changes between versions; test thoroughly in staging before production deployment

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

Fix this in Kylin Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,770
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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-2021-45457 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