Fix some security issues

[sbrunner]

Fix: GSGMF-1331

[lgtm-com]

This pull request fixes 4 alerts when merging 89155f2 into afc248c - view on LGTM.com

fixed alerts:

• 3 for Cross-site scripting
• 1 for Resolving XML external entity in user-controlled data

[gurshafriri]

👋 @sbrunner, can you elaborate a bit more about the issues at hand?
Im from Snyk and if these are indeed vulnerabilities we would like to add it to our database with full context.

[sbrunner]

@gurshafriri
I just change the title, for me, its potential security vulnerabilities detected by CodeQL I provide the links in the commits, all fixed issues:

• https://github.com/mapfish/mapfish-print/security/code-scanning/3?query=ref%3Arefs%2Fheads%2Fmaster
• https://github.com/mapfish/mapfish-print/security/code-scanning/5?query=ref%3Arefs%2Fheads%2Fmaster
• https://github.com/mapfish/mapfish-print/security/code-scanning/6?query=ref%3Arefs%2Fheads%2Fmaster
• https://github.com/mapfish/mapfish-print/security/code-scanning/7?query=ref%3Arefs%2Fheads%2Fmaster

[sbrunner]

I also publish my 2 first GitHub Security Advisories.

[gurshafriri]

@sbrunner thanks - but the links are broken for us.
Do you have the GitHub Security Advisory ID's?

[sbrunner]

Like this?

• GHSA-w534-q4xf-h5v2
• GHSA-vjv6-gq77-3mjw