Summary
Ajax Pro Cross-site Scripting
Overview
Affected versions of this package are vulnerable to Deserialization of Untrusted Data due to the possibility of deserialization of arbitrary JavaScript objects.
Description
Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted websites. XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.
XSS effects vary in range from petty nuisance to significant security risk, depending on the sensitivity of the data handled by the vulnerable site and the nature of any security mitigation implemented by the site's owner network.
Releases
Releases before version 21.12.22.1 are affected. Please be careful to download any binary DLL from other web sites, especially we found NuGet packages not owned by us that contain vulnerable versions.
Workarounds
A workaround exists that replaces one of the core JavaScript files embedded in the library. Using a XML configuration allows to replace the default JavaScript code to be replaced with the version on GitHub.
<configuration>
<configSections>
<sectionGroup name="ajaxNet">
<section name="ajaxSettings" type="AjaxPro.AjaxSettingsSectionHandler,AjaxPro.2" requirePermission="false" restartOnExternalChanges="true"/>
</sectionGroup>
</configSections>
<ajaxNet>
<ajaxSettings>
<coreScript>~/ajaxpro-core-fixed.js</coreScript>
</ajaxSettings>
</ajaxNet>
</configuration>
Copy the file core.js from the main project folder to your web server root folder and rename that ajaxpro-core-fixed.js.
Clients need to refresh the web page to download the changed JavaScript code.
References
Commit fixing the issue: c89e39b9679fcb8ab6644fe21cc7e652cb615e2b
Note: the official Ajax.NET Professional (AjaxPro) NuGet package is available here: https://www.nuget.org/packages/AjaxNetProfessional/
Impact
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2023-49289 has a CVSS score of 6.3 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (21.12.22.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2023-49289? CVE-2023-49289 is a medium-severity cross-site scripting (XSS) vulnerability in AjaxNetProfessional (nuget), affecting versions < 21.12.22.1. It is fixed in 21.12.22.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2023-49289? CVE-2023-49289 has a CVSS score of 6.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of AjaxNetProfessional are affected by CVE-2023-49289? AjaxNetProfessional (nuget) versions < 21.12.22.1 is affected.
- Is there a fix for CVE-2023-49289? Yes. CVE-2023-49289 is fixed in 21.12.22.1. Upgrade to this version or later.
- Is CVE-2023-49289 exploitable, and should I be worried? Whether CVE-2023-49289 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-49289 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-49289? Upgrade
AjaxNetProfessionalto 21.12.22.1 or later.