Nokogiri::XML::Schema trusts input by default, exposing risk of XXE vulnerability

Exploitation

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

CVSS

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

EPSS

• CVE-2020-26247: 1.18% estimated exploitation activity in the next 30 days; percentile 67.77 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Severity Nokogiri maintainers have evaluated this as Low Severity (CVSS3 2.6). Description In Nokogiri versions <= 1.11.0.rc3, XML Schemas parsed by Nokogiri::XML::Schema are trusted by default, allowing external resources to be accessed over the network, potentially enabling XXE or SSRF attacks. This behavior is counter to the security policy followed by Nokogiri maintainers, which is to treat all input as untrusted by default whenever possible. Please note that this security fix was pushed into a new minor version, 1.11.x, rather than a patch release to the 1.10.x branch, because it is a breaking change for some schemas and the risk was assessed to be "Low Severity". Affected Versions Nokogiri <= 1.10.10 as well as prereleases 1.11.0.rc1, 1.11.0.rc2, and 1.11.0.rc3 Mitigation There are no known workarounds for affected versions. Upgrade to Nokogiri 1.11.0.rc4 or later. If, after upgrading to 1.11.0.rc4 or later, you wish to re-enable network access for resolution of external…

Published by the source

30 Dec 2020, 18:35 UTC

Last modified by the source

4 May 2023, 19:54 UTC

Source last checked

26 Oct 2026, 15:47 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-vr8q-g5c7-m54m

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# Patch Next advisory brief: CVE-2020-26247

Advisory: Nokogiri::XML::Schema trusts input by default, exposing risk of XXE vulnerability
IDs: CVE-2020-26247, GHSA-vr8q-g5c7-m54m
Record: https://patchnext.com/advisories/cve-2020-26247 (revision 1, source checked 26 Oct 2026, 15:47 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nokogiri 1.11.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems nokogiri: affected <= 1.10.10; fixed in 1.11.0

## 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-vr8q-g5c7-m54m (GitHub-reviewed advisory GHSA-vr8q-g5c7-m54m lists affected ranges: RubyGems nokogiri >=0 <=1.10.10)

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