\ converted to \textbackslash when between $

[VictorDubois]

Describe your issue

Hello,

I have found an error, when you save a page with a \ symbol, which is between two $ symbols. It is replaced by \textbackslash, even if the symbols are several paragraphs apart.

$
`\`
$

Workaround (if it is possible for you): add a useless extra $ symbol before the \ symbol

Device and settings

Ubuntu 24.04, Chrome (but unrelated, as the error is server-side)

Steps to reproduce

• Create a new page, with:

$
`\`
$

• Save

• Reopen the editor, the content is now

$
`\textbackslash`
$

Screenshots (optional)

left: editor
center: preview (agrees with me to what the output should look like)
right: actual page after saving (does not agree with the preview)

Extra fields

• I'd like to work on this issue

[VictorDubois]

I am not able to reproduce this bug with just https://parsedown.org/demo
It might be linked to its safemode, though

[ffiesta]

Hello, i try this error, and it happened, when wikidocs save! I think this happened because the security xbow or escape entities.

As another example, when we try to add some ascii caracter code, the first time wikidocs save, it save it as ascii, ... in first opening to edit, it convert code and we lost the ascii code text. To prevent this we need to add \ascii.

[ffiesta]

See #254

[leomoon]

This filter is designed as a security measure to prevent "math mode escaping" - where malicious users could use backslashes to break out of KaTeX math mode and potentially inject harmful content. The \textbackslash is KaTeX's safe way to render a literal backslash character.

The conversion is intentional from a security standpoint, but it may not be the desired behavior for legitimate use cases where users want to display literal backslashes in their math expressions.

I'll see if I can make it better.

[ffiesta]

Hi @leomoon

Like as you say "...but it may not be the desired behavior for legitimate use cases where users want to display literal backslashes in their math expressions." and on code.

The problem is that convert code blocks and this cannot happened.

In the end this error could be created how wikidocs works on create/edit file content.md and not by security implementation.