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Fencer Vulns
medium 5.3

CVE-2026-57436 json

Nokogiri: Possible Use-After-Free when setting `Document#root=` to an invalid node type

published 2026-06-19 4 mo ago modified 2026-10-25 14 d ago also GHSA-wjv4-x9w8-wm3h , EUVD-2026-39427

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri::XML::Document#root= validated only that the new root was a Nokogiri::XML::Node, allowing a DTD node to be set as the document root. The result is a heap use-after-free during garbage collection or finalization, leading to an invalid memory read or potentially a segfault. This vulnerability is fixed in 1.19.4.

Patch / fix

  • rubygems nokogiri 1.19.4
  • nokogiri nokogiri 1.19.4
  • ruby-nokogiri Debian 14 1.19.4+dfsg-1

debian advisories DEBIAN-CVE-2026-57436

  • ruby-nokogiri Alpine 3.24 1.19.4-r0

alpine advisories ALPINE-CVE-2026-57436

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • rubygem-nokogiri Azure Linux 3.0 1.19.4-1

azure linux advisories AZL-91077

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-57436 updated cvss 3.7

nokogiri: rubygem-nokogiri: Nokogiri: Denial of Service via heap use-after-free

  • Red Hat 3scale API Management Platform 2 3scale-amp21/zync, 3scale-amp22/zync, 3scale-amp21/system, 3scale-amp22/system, 3scale-amp21/backend, 3scale-amp22/backend, +9 more Red Hat Satellite 6 rubygem-nokogiri
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
4 mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 1.7 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
CNA 4.0 1.7 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
rubygems nokogiri
<1.19.4
1.19.4

Affected products

  • sparklemotion nokogiri

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.