Impact

The REXML gems from 3.3.3 to 3.4.1 has a DoS vulnerability when parsing XML containing multiple XML declarations.
If you need to parse untrusted XMLs, you may be impacted to these vulnerabilities.

Patches

The REXML gem 3.4.2 or later include the patches to fix these vulnerabilities.

Workarounds

Don't parse untrusted XMLs.

References

• https://www.ruby-lang.org/en/news/2025/09/18/dos-rexml-cve-2025-58767/ : An announce on www.ruby-lang.org