Remove redundant REXML pre-parse in Saml::Base.parse - #195
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Nokogiri (via libxml2) has blocked entity-expansion DoS natively since 2.9.2, and the parameter-entity bypass (CVE-2021-3541) has been covered since Nokogiri 1.11.4. The REXML pre-parse was only needed as a tripwire in 2014 before Nokogiri had these protections, and its RuntimeError wasn't even caught by the rescue clause below it, so it leaked an undocumented raw exception instead of the library's usual Saml::Errors::UnparseableMessage. Refs digidentity#194
rexml is no longer used now that base.rb only parses via Nokogiri.
The nokogiri floor is bumped to 1.11.4, the first version that fixes
the parameter-entity ("Parameter Laughs") bypass, CVE-2021-3541.
Refs digidentity#194
Hash.from_xml used ActiveSupport's REXML backend, which is no longer a guaranteed dependency now that rexml has been dropped. Assert on the generated SOAP header directly via Nokogiri instead. Refs digidentity#194
benoist
approved these changes
Aug 16, 2026
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Summary
Closes #194 (see issue for full analysis/verification of why this is safe).
Nokogiri/libxml2 has natively blocked entity-expansion DoS, including the parameter-entity bypass, since Nokogiri 1.11.4, so the REXML pre-parse tripwire is redundant and can be removed, along with the
rexmldependency it required.Changes
lib/saml/base.rb: remove the REXML pre-parse and its now-unneededREXML::ParseExceptionrescue.saml.gemspec: drop therexmldependency, requirenokogiri >= 1.11.4, < 2.0.spec/lib/saml/base_spec.rb: update specs for the new behavior.spec/lib/saml/complex_types/request_abstract_type_spec.rb: the SOAP header spec usedHash.from_xml, which relied on ActiveSupport's REXML backend — no longer a guaranteed dependency. Rewritten to assert on the generated SOAP header via Nokogiri directly.Test plan
bundle exec rspec spec/lib/saml/base_spec.rb spec/lib/saml/complex_types/request_abstract_type_spec.rbpasses