CVE-2018-20000: Bw webdav Bw-webdav Vulnerability

HIGH
Advisory Identifier: GHSA-5p52-j8pw-j7x5
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CVSS 7.5
CWE-611
Published
Advisory Summary

CVE-2018-20000 is a HIGH (CVSS 7.5) bw-webdav vulnerability (CWE-611: Improper Restriction of XML External Entity Reference) affecting Bw webdav libraries in the Maven ecosystem. The issue involves bw-webdav. Remediation is available by upgrading affected packages to version 4.0.3.

CVE-2018-20000 at a Glance

CVE Identifier CVE-2018-20000
GHSA Identifier GHSA-5p52-j8pw-j7x5
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-611: Improper Restriction of XML External Entity Reference
Affected Product Bw webdav
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2018-20000

To remediate this vulnerability, upgrade all affected Bw webdav dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.bedework:bw-webdav fixed: 4.0.3 
<dependency>
    <groupId>org.bedework</groupId>
    <artifactId>bw-webdav</artifactId>
    <version>4.0.3</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.bedework

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2018-20000, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.bedework

Analyze the terminal output to locate any version of Bw webdav in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.0.3), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.bedework 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-611: Improper Restriction of XML External Entity Reference, where the product processes an xml document that can contain xml entities with uris that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output. In Bw webdav, 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

Apereo Bedework bw-webdav before 4.0.3 allows XXE attacks, as demonstrated by an invite-reply document that reads a local file, related to webdav/servlet/common/MethodBase.java and webdav/servlet/common/PostRequestPars.java.

CVE-2018-20000 Affected Bw webdav Versions

1 component(s)
Fixed Versions:
4.0.3
Product / Package Ecosystem Affected Versions Fixed Version
org.bedework:bw-webdav
maven/org.bedework/bw-webdav
Maven
≥ 4.0.1
< 4.0.3
4.0.3

References

NVD — CVE-2018-20000 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-20000
Bw webdav Source Repository REPOSITORY
https://github.com/Bedework/bw-webdav/pull/1
Bw webdav Source Repository REPOSITORY
https://github.com/Bedework/bw-webdav
Bw webdav Source Repository REPOSITORY
https://github.com/Bedework/bw-webdav/compare/bw-webdav-4.0.2...bw-webdav-4.0.3
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-5p52-j8pw-j7x5

Frequently Asked Questions

What is CVE-2018-20000?
CVE-2018-20000 is a security vulnerability in Bw webdav involving bw-webdav under CWE-611: Improper Restriction of XML External Entity Reference.
Which Bw webdav versions are affected?
Affected versions include releases prior to 4.0.3 across affected packages: org.bedework:bw-webdav.
What version fixes CVE-2018-20000?
Upgrading to 4.0.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is bw-webdav affected?
Yes, org.bedework:bw-webdav is affected in releases prior to 4.0.3. Upgrade your dependency to 4.0.3 or later.
What is the CVSS score of CVE-2018-20000?
CVE-2018-20000 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2018-20000?
CVE-2018-20000 is classified under CWE-611: Improper Restriction of XML External Entity Reference (The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.).
How can I check Maven dependencies for CVE-2018-20000?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.bedework'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5p52-j8pw-j7x5",
  "modified" : "2024-05-15T06:56:33Z",
  "published" : "2018-12-19T19:24:52Z",
  "aliases" : [ "CVE-2018-20000" ],
  "summary" : "Improper Restriction of XML External Entity Reference in bedework:bw-webdav",
  "details" : "Apereo Bedework bw-webdav before 4.0.3 allows XXE attacks, as demonstrated by an invite-reply document that reads a local file, related to webdav/servlet/common/MethodBase.java and webdav/servlet/common/PostRequestPars.java.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.bedework:bw-webdav"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.1"
      }, {
        "fixed" : "4.0.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-20000"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Bedework/bw-webdav/pull/1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Bedework/bw-webdav"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Bedework/bw-webdav/compare/bw-webdav-4.0.2...bw-webdav-4.0.3"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-5p52-j8pw-j7x5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-611" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-06-16T21:16:51Z",
    "nvd_published_at" : null
  }
}