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UndertowApplication · Redhat

CVE-2020-1757

HIGH · 8.1 CVSS v3.1 Published 2020-04-21
Fix available
A fix is available. Upgrade to 2.1.0 or later.
See remediation →
87/100
Remediation priority · High
Remotely reachable 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 all undertow-2.x.x SP1 versions prior to undertow-2.0.30.SP1, all undertow-1.x.x and undertow-2.x.x versions prior to undertow-2.1.0.Final, where the Servlet container causes servletPath to normalize incorrectly by truncating the path after semicolon which may lead to an application mapping resulting in the security bypass.

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

The Undertow servlet container incorrectly normalizes servletPath by truncating the path after a semicolon character. This path normalization flaw can allow attackers to bypass security constraints or application mappings that rely on the full URL path, potentially exposing protected resources.

MitigationUpgrade Undertow to version 2.0.30.SP1, 2.1.0.Final, or later which contains the fix for the semicolon truncation issue. If immediate upgrade is not feasible, audit all servlet and security mappings to ensure they cannot be bypassed using semicolon-based path manipulation.

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
UndertowApplication
Affected:< 2.1.0= 2.0.0= 2.0.25= 2.0.26= 2.0.28
Jboss Data GridApplication
Affected:= 7.0.0
Jboss Enterprise Application PlatformApplication
Affected:= 7.0.0
Jboss FuseApplication
Affected:= 6.0.0= 7.0.0
Openshift Application RuntimesApplication
Affected:all versions
Single Sign OnApplication
Affected:= 7.0

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/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 Undertow installation and version
    Locate the undertow-core jar file in the deployment, or inspect the pom.xml/dependency management files for the undertow version. Check application manifest files (MANIFEST.MF) for embedded Undertow version details.
    Affected if Undertow version is 2.0.0, 2.0.25, 2.0.26, 2.0.28, or any version below 2.1.0 (excluding 2.0.30.SP1 and later fixes)
  2. Confirm JBoss/WildFly wrapper version
    If using JBoss Enterprise Application Platform, WildFly, or JBoss Fuse, check the server version banner or the jboss-modules.jar version. For Openshift Application Runtimes, check the runtime version in the service definition.
    Affected if The underlying Undertow component matches the vulnerable versions listed above regardless of the wrapper product name
  3. Verify servlet mapping configuration
    Inspect the deployment descriptor (web.xml or the equivalent annotation-based configuration) for servlet-mapping and security-constraint definitions. Look for url-pattern elements that define path-based access controls.
    Affected if The application uses exact-path servlet mappings or security constraints that rely on the full request path for access control decisions
  4. Test semicolon path truncation behavior
    Send a test request to a protected endpoint with a semicolon and additional path segments (e.g., /protected;anytext/sensitive.jsp). Compare the servletPath received by the application against the expected full path without semicolons.
    Affected if The servletPath returned to the application truncates the path at the semicolon character, exposing the protected resource despite the security mapping

A system is affected if it runs any of the vulnerable Undertow versions (below 2.1.0, excluding 2.0.30.SP1+) and uses servlet or security mappings that depend on the full request path for access control.

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.

From vendor data
Upgrade available Upgrade to 2.1.0 or later
Fixed in 2.1.0
Interim mitigation

Upgrade Undertow to version 2.0.30.SP1, 2.1.0.Final, or later which contains the fix for the semicolon truncation issue. If immediate upgrade is not feasible, audit all servlet and security mappings to ensure they cannot be bypassed using semicolon-based path manipulation.

Fix this in Undertow Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,220
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,552.

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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-2020-1757 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