Medium Memory corruption

CVE-2026-57438 — Nokogiri: Possible Use-After-Free in XInclude Processing

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, XInclude substitution performed by Nokogiri::XML::Node#do_xinclude replaced each <xi:include> in place, freeing the include node along with its children (such as <xi:fallback> and its descendants) and any namespaces declared on them. If an application had already exposed one of those nodes or namespaces to Ruby, the corresponding Ruby object was left pointing at freed memory. Using the object could result in invalid reads or writes to memory. This vulnerability is fixed in 1.19.4.

Published Jun 25, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.1% (30-day exploitation probability)+0
Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.13%

ahead of 2% of scored CVEs · Oct 14, 2026

Affects

Nokogiri

CVSS base

6.6

Medium · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Nokogiri Nokogiri, Sparklemotion Nokogiri).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Nokogiri	Nokogiri	< 1.19.4	Vulnerable	NIST National Vulnerability Database
Sparklemotion	Nokogiri	version < 1.19.4	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
2.2	CVSS 4.0	Low	—	—	security-advisories@github.com via NIST National Vulnerability Database
2.2	CVSS 4.0	Low	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
6.6	CVSS 3.1	Medium	1.8	4.7	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-416 · Use After Free

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.13%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

2026
Affected products added · sparklemotion/nokogiri
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 6.6
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Jun 25, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

github.com/sparklemotion/nokogiri/security/advisories/GHSA-wfpw-mmfh-qq69
Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database

Elsewhere on this site

Nokogiri
every CVE for this vendor

Memory corruption
same class

CWE-416
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-79770 Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer Aug 25, 2026
Medium CVE-2026-79771 Nokogiri before 1.19.3 Memory Leak via XSLT Transform Aug 25, 2026
Medium CVE-2026-79772 Nokogiri before 1.19.1 Unchecked Return Value canonicalize Aug 25, 2026
Medium CVE-2026-79769 Nokogiri before 1.19.4 Invalid Memory Read via initialize_copy_with_args Aug 25, 2026
High CVE-2026-57435 Nokogiri: Possible Use-After-Free when setting an attribute value via `Nokogiri::XML::Attr#value=` or `#content=` Jun 25, 2026
Medium CVE-2026-57436 Nokogiri: Possible Use-After-Free when setting `Document#root=` to an invalid node type Jun 25, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-57438 is "Nokogiri: Possible Use-After-Free in XInclude Processing", rated Medium. It affects Nokogiri (Nokogiri); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.6 describes technical severity. EPSS 0.13% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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