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Phu Nguyen
Oct 25, 2023
(4 votes)

Vulnerability in EPiServer.Forms

We recently fixed a potential security vulnerability for the Optimizely Forms addon, customers may face this issue with any Forms version, the problem will happen when using a CMS function without noticing its noted behaviors. It could lead to losing security protection for some of the end-users' data.

Overall, the risk of vulnerability is high, especially if your website uses content indexing services (like Find or other search engines).


The issue has been fixed in EPiServer.Forms v5.7.0 (AFORM-3620) for CMS 12 and v4.31.0 for CMS 11. Please upgrade to those versions as soon as possible.

For DXP service customers:

  • Mitigation is in place for all DXP service customers.
  • Update (October 27): To clarify, we have mitigated existing vulnerable vectors, but packages SHOULD be updated to mitigate the risk of reintroducing the vulnerability!

Affected versions
Any Forms version before 5.7.0 (CMS12) or Forms 4.31.0 (CMS11). 

If using the affected versions of EPiServer.Forms listed above, please update to version 5.7.0 (CMS12) or Forms 4.31.0 (CMS11).

Please reach out to our support for further guidance by email to or submit a request at


If you have any questions, please contact our support team (with assistance from our security engineering team) at

Risk definitions

Low – little to no potential impact on Optimizely or customer environments/data. Vulnerability has low exploitability, for example: requirement for local or physical system access, zero reachability to/executability within Optimizely products/code.

Medium – some potential impact on Optimizely or customer environments/data. Vulnerability has medium exploitability, for example: requirement to be located on the same local network as the target, requirement for an individual to be manipulated via social engineering, requirement for user privileges, vulnerability achieves limited access to Optimizely products/code.

High – high potential impact on Optimizely or customer environments/data.  Vulnerability has high exploitability, for example:  achieves high level access to Optimizely products/code, could elevate privileges, could result in a significant data loss or downtime.

Critical – very significant potential impact on Optimizely or customer environments/data.  Vulnerability has very high exploitability, for example: achieves admin/root-level access to Optimizely products/code.  Vulnerability does not require any special authentication credentials/knowledge of Optimizely products/environments.

Oct 25, 2023


Matthew Boniface
Matthew Boniface Oct 26, 2023 11:02 PM

We are just about to DNS cutover for go-live for a customer on Monday (30th October) and so this post is very concerning for us!
Unfortunately, the post is too ambiguous to make an effective assessment whether this is needing to be fixed (and regression tested) before we go-live.
The post does not detail what the exploit is, so I cannot determine how/if this vulnerability should be a concern for our client and/or if there is any other workarounds.
Also, the mitigations suggest that the packages should be upgraded but then separately states "Mitigation is in place for all DXP service customers". These come across as conflicting statements - it is unclear if that latter statement means that a DXP hosted client does therefore not need to update the packages?

Phu Nguyen
Phu Nguyen Oct 27, 2023 01:17 AM

Hi Matthew Boniface, I know your concern, and I must say we're so sorry for that, but this blog is public, so we cannot give too many details about this vulnerability here.
But I can tell you that not all customers using Forms have this issue on their sites, and this security issue is not easily exploitable. We also took several actions to patch the issue and protect our customers' data on DXP, so all DXP customers' data is now secure. But for safety reasons, we still recommend you update Forms to the latest version.

Tomas Hensrud Gulla
Tomas Hensrud Gulla Oct 29, 2023 08:32 PM

Is the email address for questions correct?

Bien Nguyen
Bien Nguyen Oct 30, 2023 02:38 AM

Tomas Hensrud Gulla Not sure why your outlook says that but yes, it's the correct email address. Maybe it's the dot (.) at the end that caused it?

Tomas Hensrud Gulla
Tomas Hensrud Gulla Oct 30, 2023 09:05 AM

🤦‍♂️You are absolutely correct...

Aniket Dec 8, 2023 12:10 AM

Looks like there's a hard dependency on .NET 6.0. We have a client on .NET Framework 4.8.1 so this cannot be installed on CMS 11? Am I missing something?

If I try to install I get the following error:

You are trying to install this package into a project that targets '.NETFramework,Version=v4.8', but the package does not contain any assembly references or content files that are compatible with that

Matthew Boniface
Matthew Boniface Dec 8, 2023 01:49 AM

Hi Aniket,

If you install EPiServer.Forms 4.31.0 ( (i.e. v4.31.0) it won't have a dependency on .NET 6 and should work fine on your .NET 4.8.1

Kind regards, Matt

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