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🛡️ CVE-2026-57234 — nokogiri

🟢 CVSS 2.0 — Low ✅ No Known Exploit CWE-178 OSV
2.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

Summary

The NONET parse option, which Nokogiri turns on by default for Nokogiri::XML::Schema (see [CVE-2020-26247](https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-vr8q-g5c7-m54m)), 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:

1. Ensure the input is trusted. Do not enable this option for untrusted input.

2. Pass a Nokogiri::XML::ParseOptions with the NONET flag turned off:

``` ruby

# 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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs low-level privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: Required — someone has to click, open or visit something.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-57234 is classified as CWE-178: Improper Handling of Case Sensitivity. The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.

Affected software

CVE-2026-57234 is recorded against 1 package.

  • nokogiri (fixed in 1.19.4)

Timeline and source

Published on 19 June 2026 and last revised on 8 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Package)

Other advisories for this package

nokogiri has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-178: Improper Handling of Case Sensitivity) in other software:

Details

Severity LOW
CVSS Score 2.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
CWE CWE-178
Public Exploit ✅ No
Source OSV
Published 2026-06-19
Updated 2026-08-20
Modified 2026-07-08
Fix URL N/A

Affected Packages

Software From version Fixed in
nokogiri — 1.19.4

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