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Fencer Vulns
medium 6.5

CVE-2017-18258 json

Uncontrolled resource consumption in nokogiri

published 2018-04-08 8 y ago modified 2026-10-14 25 d ago also GHSA-882p-jqgm-f45g , EUVD-2018-0189

cvss
6.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.7%
EPSS 2.7% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

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.

Patch / fix

  • rubygems nokogiri 1.8.2
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • libxml2 Debian 14, Debian 13, Debian 12 2.9.10+dfsg-2

debian advisories DEBIAN-CVE-2017-18258

  • libxml2 Ubuntu 14.04 LTS 2.9.1+dfsg1-3ubuntu4.13
  • libxml2 Ubuntu 16.04 LTS 2.9.3+dfsg1-1ubuntu0.6
  • libxml2 Ubuntu 18.04 LTS 2.9.4+dfsg1-6.1ubuntu1.2

ubuntu advisories UBUNTU-CVE-2017-18258

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libxml2 RHEL 7 2.9.1-6.el7.4
  • libxml2-python RHEL 7 2.9.1-6.el7.4

red hat advisories RHSA-2020:1190

  • libxml2 SLES for SAP 12 SP3, SLES 12 SP3, SLED 12 SP3 +1 more 2.9.4-46.15.1
  • python-libxml2 SLES for SAP 12 SP3, SLES 12 SP3, SLED 12 SP3 2.9.4-46.15.1

suse advisories SUSE-SU-2018:3081-1

  • libxml2 Arch Linux 2.9.6+3+g5af594d8-1

arch linux advisories AVG-671

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-2017-18258 updated cvss 3.5

libxml2: Unrestricted memory usage in xz_head() function in xzlib.c

  • Red Hat Enterprise Linux 8 mingw-libxml2, mingw32-libxml2, mingw64-libxml2 Red Hat JBoss Core Services libxml2
    affected: no fix available
  • Red Hat Ansible Tower 3.5 for RHEL 7 Server ansible-tower-35/ansible-tower 3.5.6-1
    fixed: vendor fix RHBA-2020:1539
  • Red Hat Ansible Tower 3.6 for RHEL 7 ansible-tower-36/ansible-tower 3.6.4-1
    fixed: vendor fix RHBA-2020:1540
  • Red Hat Enterprise Linux Client (v. 7) libxml2 2.9.1-6.el7.4, libxml2-python 2.9.1-6.el7.4 Red Hat Enterprise Linux Client Optional (v. 7) libxml2-devel 2.9.1-6.el7.4, libxml2-static 2.9.1-6.el7.4, libxml2-debuginfo 2.9.1-6.el7.4 Red Hat Enterprise Linux ComputeNode (v. 7) libxml2 2.9.1-6.el7.4, libxml2-python 2.9.1-6.el7.4 Red Hat Enterprise Linux ComputeNode Optional (v. 7) libxml2-devel 2.9.1-6.el7.4, libxml2-static 2.9.1-6.el7.4, libxml2-debuginfo 2.9.1-6.el7.4 Red Hat Enterprise Linux Server (v. 7) libxml2 2.9.1-6.el7.4, libxml2-python 2.9.1-6.el7.4 Red Hat Enterprise Linux Server Optional (v. 7) libxml2-static 2.9.1-6.el7.4, libxml2-debuginfo 2.9.1-6.el7.4
    +2 more products
    Red Hat Enterprise Linux Workstation (v. 7) libxml2 2.9.1-6.el7.4, libxml2-python 2.9.1-6.el7.4 Red Hat Enterprise Linux Workstation Optional (v. 7) libxml2-static 2.9.1-6.el7.4, libxml2-debuginfo 2.9.1-6.el7.4
    fixed: vendor fix RHSA-2020:1190
  • Red Hat JBoss Core Services
    fixed: vendor fix RHSA-2018:2486
  • Red Hat Enterprise Linux 5 libxml2 Red Hat Enterprise Linux 6 libxml2, libxml2-python Red Hat Enterprise Linux 8 libxml2, python3-libxml2 Red Hat JBoss Web Server 3 libxml2
    not affected: vulnerable code not present

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 ICSA-23-348-10 updated cvss 6.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

2.73% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P
GitHub 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
rubygems nokogiri
<1.8.2
1.8.2

Affected products

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

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.