Nokogiri: XML::Schema on JRuby allows network requests when NONET is set, bypassing CVE-2020-26247

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

2.6 · CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary The NONET parse option, which Nokogiri turns on by default for Nokogiri::XML::Schema (see CVE-2020-26247), was not correctly enforced on the JRuby implementation. As a result, a schema parsed with default options could still cause external resources to be fetched over the network, potentially enabling SSRF or XXE attacks. Nokogiri 1.19.4 replaces the scheme denylist with an allowlist. When NONET is enabled, only local resources (a file: scheme, or a relative or absolute path with no scheme) are resolved, and every network scheme is blocked, case-insensitively. This brings the JRuby behavior in line with CRuby. Only the JRuby implementation is affected. CRuby is not affected, because libxml2's xmlNoNetExternalEntityLoader blocks all network schemes at the I/O layer regardless of scheme or case. Severity The Nokogiri maintainers have evaluated this as low severity (CVSS 2.6, CVSS:3.0/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N). It is a bypass of CVE-2020-26247, which was scored the…

Published by the source

19 Jun 2026, 16:36 UTC

Last modified by the source

19 Jun 2026, 16:36 UTC

Source last checked

26 Oct 2026, 15:52 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8678-w3jw-xfc2

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# Patch Next advisory brief: GHSA-8678-w3jw-xfc2

Advisory: Nokogiri: XML::Schema on JRuby allows network requests when NONET is set, bypassing CVE-2020-26247
IDs: GHSA-8678-w3jw-xfc2
Record: https://patchnext.com/advisories/ghsa-8678-w3jw-xfc2 (revision 1, source checked 26 Oct 2026, 15:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nokogiri 1.19.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems nokogiri: affected < 1.19.4; fixed in 1.19.4

## Suggested inspection (read-only)
- RubyGems nokogiri: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on nokogiri.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8678-w3jw-xfc2 (GitHub-reviewed advisory GHSA-8678-w3jw-xfc2 lists affected ranges: RubyGems nokogiri >=0 <1.19.4)

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