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GHSA-8678-w3jw-xfc2

LowCVSS 2.6 / 10

Published Jun 19, 2026·Last modified Jun 19, 2026

Affected Components(0)

No affected components available

Description

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 same way.

Mitigation

Upgrade to Nokogiri 1.19.4 or later.

There are no known workarounds for affected versions.

This change properly enforces NONET on JRuby, which is a breaking change for any code that (perhaps unknowingly) relied on the previous behavior to load network resources with default parse options. If you trust your input and want to allow external resources to be accessed over the network, you can explicitly disable NONET, exactly as documented for CVE-2020-26247:

Ensure the input is trusted. Do not enable this option for untrusted input.
Pass a Nokogiri::XML::ParseOptions with the NONET flag turned off:

# allows resources to be accessed over the network for trusted input
schema = Nokogiri::XML::Schema.new(trusted_schema, Nokogiri::XML::ParseOptions.new.nononet)

References

Bypass of: https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-vr8q-g5c7-m54m

Credit

This issue was responsibly reported by @bilerden.

Risk Scores

Base Score

2.6

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.

Threat Intelligence

2.4

Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.

EPSS

0.17%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit

Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Low severity

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