Steps to reproduce

• Create a Username/Password pair in Credentials both should contain dollar signs (for example u$er and pa$$word)
• Create a seed job in Jenkins
• Bind this credentials pair as env variables in the job
• Add "Process Job DSLs" step with the following in script:

println binding.variables.get('STASH_USERNAME')
println binding.variables.get('STASH_PASSWORD')

• Run the job and see both STASH_PASSWORD and STASH_USERNAME unmasked with two dollars:

Processing provided DSL script
u$$er
pa$$$$word

Workaround

If EnvInjectBuildWrapper is enabled for the job, the result will be

Processing provided DSL script
****
pa$word

 As you can see, the second dollar in a pa$$word was escaped, which is also wrong.