CVE-2021-31404: Flow server Timing Side Channel Vulnerability Vulnerability
MODERATECVE-2021-31404 is a MODERATE (CVSS 4.0) timing side channel vulnerability vulnerability (CWE-203: Observable Discrepancy) affecting Flow server libraries in the Maven ecosystem. The issue involves timing side channel vulnerability in uidl request handler in vaadin 10, 11-14, and 15-18. Remediation is available by upgrading affected packages to version 1.0.14, 2.4.7, 5.0.3.
CVE-2021-31404 at a Glance
Security Impact
CVSS: 4.0
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N).
How to Fix CVE-2021-31404
To remediate this vulnerability, upgrade all affected Flow server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>flow-server</artifactId>
<version>1.0.14</version>
</dependency><dependency>
<groupId>com.vaadin</groupId>
<artifactId>flow-server</artifactId>
<version>2.4.7</version>
</dependency><dependency>
<groupId>com.vaadin</groupId>
<artifactId>flow-server</artifactId>
<version>5.0.3</version>
</dependency>Run the following command in your project directory to verify that all resolved dependencies use the patched release:
mvn dependency:tree -Dincludes=com.vaadinHow to Check if You Are Affected
To determine whether your Java application is affected by CVE-2021-31404, inspect your build dependencies using the Maven Dependency Plugin:
mvn dependency:tree -Dincludes=com.vaadinAnalyze the terminal output to locate any version of Flow server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.14), your application is affected.
Note: The mvn dependency:tree -Dincludes=com.vaadin command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-203: Observable Discrepancy, where the product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor. In Flow server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2021-31404 Affected Flow server Versions
3 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
com.vaadin:flow-server
|
Maven |
≥ 1.0.0
< 1.0.14
|
1.0.14
|
|
com.vaadin:flow-server
|
Maven |
≥ 1.1.0
< 2.4.7
|
2.4.7
|
|
com.vaadin:flow-server
|
Maven |
≥ 3.0.0
< 5.0.3
|
5.0.3
|
References
Frequently Asked Questions
What is CVE-2021-31404?
Which Flow server versions are affected?
What version fixes CVE-2021-31404?
Is flow-server affected?
What is the CVSS score of CVE-2021-31404?
What CWE is associated with CVE-2021-31404?
How can I check Maven dependencies for CVE-2021-31404?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-xwg3-qrcg-w9x6",
"modified" : "2021-04-23T17:17:16Z",
"published" : "2021-04-19T14:51:25Z",
"aliases" : [ "CVE-2021-31404" ],
"summary" : "Timing side channel vulnerability in UIDL request handler in Vaadin 10, 11-14, and 15-18",
"details" : "Non-constant-time comparison of CSRF tokens in UIDL request handler in `com.vaadin:flow-server` versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 through 13), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.\n\n- https://vaadin.com/security/cve-2021-31404",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Maven",
"name" : "com.vaadin:flow-server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "1.0.0"
}, {
"fixed" : "1.0.14"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Maven",
"name" : "com.vaadin:flow-server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "1.1.0"
}, {
"fixed" : "2.4.7"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Maven",
"name" : "com.vaadin:flow-server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "3.0.0"
}, {
"fixed" : "5.0.3"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/vaadin/flow/security/advisories/GHSA-xwg3-qrcg-w9x6"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-31404"
}, {
"type" : "WEB",
"url" : "https://github.com/vaadin/flow/pull/9875"
}, {
"type" : "WEB",
"url" : "https://vaadin.com/security/cve-2021-31404"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-203", "CWE-208" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2021-04-16T23:16:19Z",
"nvd_published_at" : "2021-04-23T16:15:00Z"
}
}