CVE-2023-49289
Cross-site Scripting in Ajax.NET Professional
Ajax.NET Professional (AjaxPro) is an AJAX framework for Microsoft ASP.NET which will create proxy JavaScript classes that are used on client-side to invoke methods on the web server. Affected versions of this package are vulnerable cross site scripting attacks. Releases before version 21.12.22.1 are affected. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
6.3
Cross-site Scripting in Ajax.NET Professional
Ajax.NET Professional (AjaxPro) is an AJAX framework for Microsoft ASP.NET which will create proxy JavaScript classes that are used on client-side to invoke methods on the web server. Affected versions of this package are vulnerable cross site scripting attacks. Releases before version 21.12.22.1 are affected. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
CVE-2023-49289- CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L - Weakness
- CWE-79
- Updated
- 2026-11-02
EUVDEUVD-2023-3164
6.3
Ajax.NET Professional (AjaxPro) is an AJAX framework for Microsoft ASP.NET which will create proxy JavaScript classes that are used on client-side to invoke methods on the web server. Affected versions of this package are vulnerable cross site scripting attacks. Releases before version 21.12.22.1 are affected. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
EUVD-2023-3164- CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-8v6j-gc74-fmpp
6.3
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/
- Record
GHSA-8v6j-gc74-fmpp- CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L - Weakness
- CWE-79
- Updated
- 2026-11-02
NVD
6.3
Ajax.NET Professional (AjaxPro) is an AJAX framework for Microsoft ASP.NET which will create proxy JavaScript classes that are used on client-side to invoke methods on the web server. Affected versions of this package are vulnerable cross site scripting attacks. Releases before version 21.12.22.1 are affected. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
CVE-2023-49289- CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L - CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
6.3
Cross-site Scripting in Ajax.NET Professional
Ajax.NET Professional (AjaxPro) is an AJAX framework for Microsoft ASP.NET which will create proxy JavaScript classes that are used on client-side to invoke methods on the web server. Affected versions of this package are vulnerable cross site scripting attacks. Releases before version 21.12.22.1 are affected. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
CVE-2023-49289- CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L - Weakness
- CWE-79
- Updated
- 2026-11-02
OSVGHSA-8v6j-gc74-fmpp
6.3
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/
- Record
GHSA-8v6j-gc74-fmpp- CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L - Weakness
- CWE-79
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
AjaxNetProfessionalNuGet |
before 21.12.22.1 | 21.12.22.1 |
AjaxNetProfessionalNuGet |
before 21.12.22.1, plus listed versions 21.10.3021.11.2221.11.2921.12.21.121.12.8.1 |
21.12.22.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-49289 is a medium vulnerability (CVSS 6.3) in Michaelschwarz Ajax.net Professional, published December 4, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.63%, the 50th percentile. Fixed in AjaxNetProfessional 21.12.22.1.
References
github.com/michaelschwarz/Ajax.NET-Professional/security/advisories/GHSA-8v6j-gc74-fmpp
github.com/michaelschwarz/Ajax.NET-Professional/commit/c89e39b9679fcb8ab6644fe21cc7e652cb615e2b
nuget.org/packages/AjaxNetProfessional
nvd.nist.gov/vuln/detail/CVE-2023-49289
github.com/advisories/GHSA-8v6j-gc74-fmpp
github.com/CVEProject/cvelistV5/tree/main/cves/2023/49xxx/CVE-2023-49289.json
github.com/michaelschwarz/Ajax.NET-Professional