Summary

Fixes a security vulnerability in ParseTemplateConfig where certain malformed inputs could cause a runtime panic due to improper handling of empty regex matches.

Problem

The function ParseTemplateConfig was vulnerable to runtime panics when processing inputs like : or :::. The regular expression configTemplateRe.FindAllString(s, -1) would return an empty slice for such inputs, but the default case in the switch statement assumed parts[0] and parts[1] would always exist, causing an "index out of range" panic.

Solution

• Added a new case 0: to handle empty parts slices and return ErrTemplateStringEmpty
• Added comprehensive test cases for edge cases including : and :::
• Maintains backward compatibility while eliminating the panic vulnerability

Security Impact

• Before: Malformed inputs could cause runtime panics, potentially leading to denial of service
• After: Such inputs now return proper error handling instead of panicking

Changes

• config/template.go: Added case 0 handling in ParseTemplateConfig switch statement
• config/template_test.go: Added test cases for "colon_only" and "multiple_colons_only" scenarios

Testing

• ✅ All existing tests pass
• ✅ New test cases validate the fix
• ✅ Manual verification confirms vulnerability is resolved

References

• Addresses SECVULN-14566
• Follows security recommendations for input validation