CVE Intelligence
Medium Denial of service

CVE-2017-18258 — Uncontrolled resource consumption in nokogiri

The xz_head function in xzlib.c in libxml2 before 2.9.6 allows remote attackers to cause a denial of service (memory consumption) via a crafted LZMA file, because the decoder functionality does not restrict memory usage to what is required for a legitimate file.

Published Apr 8, 2018 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: mitre

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 2.7% (30-day exploitation probability)+13
  • 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
2.74%
ahead of 86% of scored CVEs · Oct 14, 2026
Affects
Xmlsoft
Libxml2 and 1 more
CVSS base
6.5
Medium · 2 source(s)

Remediation

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

  • Documented patch — git.gnome.org (NIST National Vulnerability Database)
  • Rubygems Nokogiri: fixed in version 1.8.2 — github.com (GitHub Security Advisories)

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.

  1. Identify exposed assets running the affected vendor/product/version combinations (Xmlsoft Libxml2, Rubygems Nokogiri).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  5. Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Xmlsoft Libxml2 < 2.9.6 Vulnerable NIST National Vulnerability Database
Rubygems Nokogiri < 1.8.2 Vulnerable GitHub Security Advisories

Attack characteristics

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

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

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

ScoreVersionSeverityExpl.ImpactScored by
6.5 CVSS 3.0 Medium 2.8 3.6 nvd@nist.gov via NIST National Vulnerability Database
6.5 CVSS 3.0 Medium — — GitHub, Inc. via GitHub Security Advisories
4.3 CVSS 2.0 Medium 8.6 2.9 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-770 · Allocation of Resources Without Limits or Throttling

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 2.74%

Detection

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

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Track CPU/memory spikes and availability drops correlated with request patterns.
web/proxy/WAF logsnetwork IDS/IPSresource metrics

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 14, 2026 · GitHub Security Advisories
  • Affected products added · rubygems/nokogiri
    Oct 14, 2026 · GitHub Security Advisories
  • Record published
    Oct 14, 2026
  • Fix documented
    Oct 14, 2026 · NIST National Vulnerability Database
  • Affected products added · xmlsoft/libxml2
    Oct 14, 2026 · NIST National Vulnerability Database
  • CVSS changed · 6.5
    Oct 14, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 14, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 14, 2026 · Alertas do Telegram
  • 2018
  • CVE published
    Apr 8, 2018 · mitre

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 14, 2026 – Oct 14, 2026
  • 1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

10 on the record

Elsewhere on this site

Xmlsoft
every CVE for this vendor
Denial of service
same class
CWE-770
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-11979 Stack-Based Buffer Overflow in libxml2 Jun 29, 2026
  • CVE-2026-6653 libxml2 Use-After-Free in xmlParseInternalSubset Causing Denial of Service Jun 22, 2026
  • CVE-2026-6732 Libxml2: libxml2: denial of service via crafted xsd-validated document Apr 23, 2026
  • CVE-2026-0990 Libxml2: libxml2: denial of service via uncontrolled recursion in xml catalog processing Jan 15, 2026
  • CVE-2026-0992 Libxml2: libxml2: denial of service via crafted xml catalogs Jan 15, 2026
  • CVE-2026-0989 Libxml2: unbounded relaxng include recursion leading to stack overflow Jan 15, 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 CISA SSVC assessment.
  • 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-2017-18258 is "Uncontrolled resource consumption in nokogiri", rated Medium. It affects Libxml2 (Xmlsoft); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. EPSS 2.74% 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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