Security readout for executives and security teams
Plain-English summary
This issue affects Nokogiri only when used on JRuby. In vulnerable versions, SAX parsing of untrusted XML or HTML can resolve external entities by default, which may expose sensitive data. CRuby deployments are not affected. The vendor says JRuby users should upgrade to Nokogiri 1.12.5 or later and that no workaround exists for earlier versions.
Executive priority
Treat this as a focused high-priority dependency fix for JRuby systems, especially internet-facing document ingestion paths. The scope is narrow, but the confirmed confidentiality impact and lack of workaround make upgrade the practical remediation path.
Technical view
CVE-2021-41098 is a CWE-611 XXE vulnerability in Nokogiri 1.12.4 and earlier on JRuby. Affected use is limited to listed SAX and PushParser classes parsing untrusted documents. CVSS 3.0 is 7.5 with network attack vector, low complexity, no privileges, no user interaction, and high confidentiality impact.
Likely exposure
Exposure is likely in JRuby applications that depend on Nokogiri before 1.12.5 and parse attacker-controlled XML or HTML through the affected SAX or PushParser classes. CRuby users are explicitly out of scope. Applications using other Nokogiri parsing paths are not confirmed affected by the provided sources.
Exploitation context
The CVE is not listed as KEV in the supplied data, and no cited source states active exploitation. The risk is still material because the CVSS vector indicates remote, unauthenticated, low-complexity confidentiality impact when vulnerable JRuby parsing paths receive untrusted documents.
Researcher notes
Affected classes include Nokogiri::XML::SAX::Parse, Nokogiri::HTML4::SAX::Parser and alias, XML SAX PushParser, and HTML4 SAX PushParser and alias. The key boundary is JRuby plus untrusted document parsing. The provided sources do not identify affected CPEs or active exploitation.
Mitigation direction
- Upgrade JRuby deployments to Nokogiri 1.12.5 or later.
- Do not rely on a workaround for Nokogiri 1.12.4 or earlier.
- Prioritize services that parse user-supplied XML or HTML.
- Confirm CRuby-only deployments are not mistakenly scoped as affected.
- Review the vendor advisory before making remediation exceptions.
Validation and detection
- Inventory applications running Nokogiri on JRuby.
- Confirm installed Nokogiri versions are 1.12.5 or later.
- Search code for affected SAX and PushParser class usage.
- Verify whether those parsers process untrusted documents.
- Document CRuby-only applications as not affected, with runtime evidence.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CWE-611: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-41098 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.5HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-2rr5-8q37-2w7hCVE reference · x_refsource_CONFIRM
- https://github.com/sparklemotion/nokogiri/commit/5bf729ff3cc84709ee3c3248c981584088bf9f6dCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Restriction of XML External Entity Reference
Improper Restriction of XML External Entity Reference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.