Home/CVE/The REXML gem before 3.2.5 in Ruby before 2.6.7, 2.7.x before 2.7.3, and 3.x before 3.0.1 does not properly address XML
CVE

CVE-2021-28965

The REXML gem before 3.2.5 in Ruby before 2.6.7, 2.7.x before 2.7.3, and 3.x before 3.0.1 does not properly address XML

The REXML gem before 3.2.5 in Ruby before 2.6.7, 2.7.x before 2.7.3, and 3.x before 3.0.1 does not properly address XML round-trip issues. An incorrect document can be produced after parsing and serializing.

HIGH · CVSS 7.5 EPSS 0.00576
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules3 YARA rules0
▤

Affected Products & Versions

5
ruby-lang rexml< 3.2.5
ruby-lang ruby< 2.6.7
ruby-lang ruby>= 2.7.0 and < 2.7.3
ruby-lang ruby>= 3.0.0 and < 3.0.1
fedoraproject fedoraall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
RubyGems rexml HIGH fixed in 3.2.5
◈

Sigma Hunt Rules

3
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productmediumRuby on Rails Framework Exceptions
productmediumPotential Ruby Reverse Shell
productmediumRuby Inline Command Execution
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD21 Apr 2021 · 07:15 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
⚑

Vendor Advisories

23
rhsaRHSA-2026:7307Moderate
rhsaRHSA-2026:8838Moderate
rhsaRHSA-2026:7305Moderate
suse-csafopenSUSE-SU-2025:15819-1
suse-csafopenSUSE-SU-2025:14621-1
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WTVFTLFVCSUE5CXHINJEUCKSHU4SWDMT/
https://security.netapp.com/advisory/ntap-20210528-0003/Third Party Advisory
https://www.ruby-lang.org/en/news/2021/04/05/xml-round-trip-vulnerability-in-rexml-cve-2021-28965/Vendor Advisory
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