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Fencer Vulns
critical 9.8

CVE-2016-9063 json

An integer overflow during the parsing of XML using the Expat library.

published 2018-06-11 8 y ago modified 2026-10-08 31 d ago also EUVD-2016-9884

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
5.4%
EPSS 5.4% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

An integer overflow during the parsing of XML using the Expat library. This vulnerability affects Firefox < 50.

Patch / fix

  • Mozilla Firefox 50
  • expat Debian 14, Debian 13, Debian 12 2.2.0-2

debian advisories DEBIAN-CVE-2016-9063

  • firefox Ubuntu 14.04 LTS 50.0+build2-0ubuntu0.14.04.2
  • firefox Ubuntu 16.04 LTS 50.0+build2-0ubuntu0.16.04.2

ubuntu advisories UBUNTU-CVE-2016-9063

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

  • expat Linux Micro 6.0 2.8.5-159998.1.1
  • expat SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +10 more 2.8.5-150400.3.40.1
  • python3 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +18 more 3.4.10-25.39.3
  • python3-base SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +18 more 3.4.10-25.39.2
  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +17 more 68.2.0-109.95.2
  • expat Studio Onsite 1.3, SLES for SAP 11 SP4, SLES 11 SP4 +1 more 2.0.1-88.42.3.2
  • expat SLES for SAP 12 SP3, SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2 +6 more 2.1.0-21.3.1
  • expat SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.8.5-21.55.1

suse advisories SUSE-SU-2026:24323-1SUSE-SU-2026:4623-1SUSE-SU-2026:4615-1SUSE-SU-2020:0497-1SUSE-SU-2019:2872-1SUSE-SU-2017:2375-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 50.1.0-1.1
  • expat openSUSE Tumbleweed 2.4.1-1.2

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10071-1openSUSE-SU-2024:10748-1

  • lib32-expat Arch Linux 2.2.2-1
  • expat Arch Linux 2.2.1-1
  • firefox Arch Linux 50.0-1

arch linux advisories AVG-305AVG-306AVG-72

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-2016-9063 updated cvss 9.8

firefox: Possible integer overflow to fix inside XML_Parse in Expat

  • Red Hat Enterprise Linux 5 expat Red Hat Enterprise Linux 6 expat, compat-expat1 Red Hat Enterprise Linux 7 expat Red Hat Enterprise Virtualization 3 mingw-virt-viewer, mingw32-virt-viewer, mingw64-virt-viewer Red Hat JBoss Enterprise Application Platform 6 httpd, mod_ssl, mod_ldap, httpd-tools, httpd-manual Red Hat JBoss Enterprise Web Server 2 expat
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 5 firefox, thunderbird Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 python, firefox, tkinter, python-libs, python-test, thunderbird, +1 more
    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 SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
31 d ago

Exploit prediction

5.36% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Mozilla Firefox

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound

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.