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Fencer Vulns
medium 5.5

CVE-2016-1839 json

The xmlDictAddString function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watch…

published 2016-05-20 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-2934

cvss
5.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
7.3%
EPSS 7.3% chance of exploitation in 30 days, percentile 94%
public exploits
1
Exploit-DB

Summary

The xmlDictAddString function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted XML document.

Patch / fix

  • xmlsoft libxml2 2.9.4
  • apple iphone_os 9.3.2
  • apple mac_os_x 10.11.5
  • apple tvos 9.2.1
  • apple watchos 2.2.1
  • libxml2 Debian 14, Debian 13, Debian 12 2.9.3+dfsg1-1.1

debian advisories DEBIAN-CVE-2016-1839

  • libxml2 Ubuntu 14.04 LTS 2.9.1+dfsg1-3ubuntu4.8
  • libxml2 Ubuntu 16.04 LTS 2.9.3+dfsg1-1ubuntu0.1

ubuntu advisories UBUNTU-CVE-2016-1839

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 6 2.7.6-21.el6_8.1
  • libxml2 RHEL 7 2.9.1-6.el7_2.3
  • libxml2-python RHEL 6 2.7.6-21.el6_8.1
  • libxml2-python RHEL 7 2.9.1-6.el7_2.3

red hat advisories RHSA-2016:1292

  • libxml2 SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2, SLES 12 SP2 +2 more 2.9.4-36.1
  • python-libxml2 SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2, SLES 12 SP2 +1 more 2.9.4-36.1
  • libxml2 SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +6 more 2.7.6-0.44.1
  • libxml2-python SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +5 more 2.7.6-0.44.4
  • libxml2 SLES for SAP 12 SP1, SLES for SAP 12, SLES 12 SP1 +5 more 2.9.1-24.1
  • python-libxml2 SLES for SAP 12 SP1, SLES for SAP 12, SLES 12 SP1 +3 more 2.9.1-24.1

suse advisories SUSE-SU-2017:1454-1SUSE-SU-2016:1604-1SUSE-SU-2016:1538-1

  • libxml2 openSUSE Tumbleweed 2.9.4-1.22
  • python-libxml2 openSUSE Tumbleweed 2.9.4-1.4

opensuse advisories openSUSE-SU-2024:10192-1openSUSE-SU-2024:10228-1

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-2016-1839 updated cvss 4.3

libxml2: Heap-based buffer overread in xmlDictAddString

  • Red Hat Enterprise Linux 5 libxml2
    affected: no fix planned “Will not fix”
  • Red Hat JBoss Enterprise Web Server 3 libxml2
    affected: no fix available
  • Red Hat Enterprise Linux Client (v. 7) libxml2 2.9.1-6.el7_2.3, libxml2-python 2.9.1-6.el7_2.3 Red Hat Enterprise Linux Client Optional (v. 7) libxml2-devel 2.9.1-6.el7_2.3, libxml2-static 2.9.1-6.el7_2.3, libxml2-debuginfo 2.9.1-6.el7_2.3 Red Hat Enterprise Linux ComputeNode (v. 7) libxml2 2.9.1-6.el7_2.3, libxml2-python 2.9.1-6.el7_2.3 Red Hat Enterprise Linux ComputeNode Optional (v. 7) libxml2-devel 2.9.1-6.el7_2.3, libxml2-static 2.9.1-6.el7_2.3, libxml2-debuginfo 2.9.1-6.el7_2.3 Red Hat Enterprise Linux Desktop (v. 6) libxml2 2.7.6-21.el6_8.1, libxml2-python 2.7.6-21.el6_8.1 Red Hat Enterprise Linux Desktop Optional (v. 6) libxml2-devel 2.7.6-21.el6_8.1, libxml2-static 2.7.6-21.el6_8.1, libxml2-debuginfo 2.7.6-21.el6_8.1
    +10 more products
    Red Hat Enterprise Linux HPC Node (v. 6) libxml2 2.7.6-21.el6_8.1, libxml2-python 2.7.6-21.el6_8.1 Red Hat Enterprise Linux HPC Node Optional (v. 6) libxml2-devel 2.7.6-21.el6_8.1, libxml2-static 2.7.6-21.el6_8.1, libxml2-debuginfo 2.7.6-21.el6_8.1 Red Hat Enterprise Linux Server (v. 6) libxml2 2.7.6-21.el6_8.1, libxml2-python 2.7.6-21.el6_8.1 Red Hat Enterprise Linux Server (v. 7) libxml2 2.9.1-6.el7_2.3, libxml2-python 2.9.1-6.el7_2.3 Red Hat Enterprise Linux Server Optional (v. 6) libxml2-static 2.7.6-21.el6_8.1, libxml2-debuginfo 2.7.6-21.el6_8.1 Red Hat Enterprise Linux Server Optional (v. 7) libxml2-static 2.9.1-6.el7_2.3, libxml2-debuginfo 2.9.1-6.el7_2.3 Red Hat Enterprise Linux Workstation (v. 6) libxml2 2.7.6-21.el6_8.1, libxml2-python 2.7.6-21.el6_8.1 Red Hat Enterprise Linux Workstation (v. 7) libxml2 2.9.1-6.el7_2.3, libxml2-python 2.9.1-6.el7_2.3 Red Hat Enterprise Linux Workstation Optional (v. 6) libxml2-static 2.7.6-21.el6_8.1, libxml2-debuginfo 2.7.6-21.el6_8.1 Red Hat Enterprise Linux Workstation Optional (v. 7) libxml2-static 2.9.1-6.el7_2.3, libxml2-debuginfo 2.9.1-6.el7_2.3
    fixed: vendor fix RHSA-2016:1292
  • Red Hat JBoss Core Services
    fixed: vendor fix RHSA-2016:2957

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

Timeline

  1. First public exploit (EDB-39491)
  2. Published

Exploit prediction

7.35% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-39491 libxml2 - xmlDictAddString Heap Buffer Overread dos, 2016-02-24
  • bugzilla.gnome.org https://bugzilla.gnome.org/show_bug.cgi?id=758605 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 5.5 CVSS:3.0/AV:L/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

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.