GHSA-5q99-f34m-67gc CVE-2018-11784

Apache Tomcat Open Redirect vulnerability

Medium Maven

Severity: 4.3 / 10; Medium · CVSS 3.0
Exploit chance (EPSS): 97.68%; Chance of exploitation in the next 30 days. Higher than 99.90% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-601 URL Redirection to Untrusted Site ('Open Redirect')
Fix: 8.5.34; Upgrade org.apache.tomcat.embed:tomcat-embed-core to this version or later

Description

When the default servlet in Apache Tomcat versions 9.0.0.M1 to 9.0.11, 8.5.0 to 8.5.33 and 7.0.23 to 7.0.90 returned a redirect to a directory (e.g. redirecting to '/foo/' when the user requested '/foo') a specially crafted URL could be used to cause the redirect to be generated to any URI of the attackers choice.

Affected versions

Maven

Package	Vulnerable	Fixed in
org.apache.tomcat.embed:tomcat-embed-core	`>= 8.5.0, < 8.5.34`	`8.5.34`
org.apache.tomcat.embed:tomcat-embed-core	`>= 7.0.23, < 7.0.91`	`7.0.91`
org.apache.tomcat.embed:tomcat-embed-core	`>= 9.0.0, < 9.0.12`	`9.0.12`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

org.apache.tomcat.embed:tomcat-embed-core Maven → `8.5.34`

maven

<dependency><groupId>org.apache.tomcat.embed</groupId><artifactId>tomcat-embed-core</artifactId><version>8.5.34</version></dependency>

gradle

implementation("org.apache.tomcat.embed:tomcat-embed-core:8.5.34")

Severity breakdown

CVSS 3.0 4.3

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Weakness

CWE-601: URL Redirection to Untrusted Site ('Open Redirect')

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

How to prevent it

Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. Use a list of approved URLs or domains to be used for redirection.
Architecture and Design: Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
Architecture and Design: When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to "/login.asp" and ID 2 could map to "http://www.example.com/". Features such as the ESAPI AccessReferenceMap [REF-45] provide this capability.
Architecture and Design: Ensure that no externally-supplied requests are honored by requiring that all redirect requests include a unique nonce generated by the application [REF-483]. Be sure that the nonce is not predictable (CWE-330).
Architecture and Design, Implementation: Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls. Many open redirect problems occur because the programmer assumed that certain inputs could not be modified, such as cookies and hidden form fields.
Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].

References

Advisories

Packages

github.com/apache/tomcat

Timeline

Oct 17, 2018 Published
Mar 11, 2024 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-83qj-6fr2-vhqg Apache Tomcat: Potential RCE and/or information disclosure and/or information corruption with partial PUT	Critical Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-qppj-fm5r-hxr3 HTTP/2 Stream Cancellation Attack	Medium Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-xjgh-84hx-56c5 Unrestricted Upload of File with Dangerous Type Apache Tomcat	High Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
CVE-2020-1938 Improper Privilege Management in Tomcat	Critical Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-pjfr-qf3p-3q25 When running Apache Tomcat on Windows with HTTP PUTs enabled it was possible to upload a JSP file to the server	High Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-h3x4-894j-xpx5 Apache Tomcat's FORM authentication process has an Incorrect Authorization vulnerability	Critical	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-9xv2-5v5q-p794 Apache Tomcat's DIGEST authenticator has an Authentication Bypass by Capture-replay vulnerability	Critical	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-f525-44xv-f2qj Apache Tomcat - HTTP/2 no-authority bypass of strict SNI validation	Critical	Also affects org.apache.tomcat.embed:tomcat-embed-core

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