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Fencer Vulns
high 7.5

CVE-2016-5300 json

The XML parser in Expat does not use sufficient entropy for hash initialization, which allows context-dependent attackers to cause a denial…

published 2016-06-16 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6251

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
6.5%
EPSS 6.5% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

The XML parser in Expat does not use sufficient entropy for hash initialization, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted identifiers in an XML document. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-0876.

Patch / fix

  • libexpat_project libexpat 2.2.0
  • expat Debian 14, Debian 13, Debian 12 2.1.1-3

debian advisories DEBIAN-CVE-2016-5300

  • expat Ubuntu 14.04 LTS 2.1.0-4ubuntu1.3
  • expat Ubuntu 16.04 LTS 2.1.0-7ubuntu0.16.04.2

ubuntu advisories UBUNTU-CVE-2016-5300

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 SLES for SAP 12 SP2, SLES for SAP 12 SP1, SLES for Raspberry Pi 12 SP2 +6 more 2.1.0-20.2
  • expat Studio Onsite 1.3, SLES for SAP 11 SP4, SLES 11 SP4 +1 more 2.0.1-88.41.1

suse advisories SUSE-SU-2017:0424-1SUSE-SU-2017:0415-1

  • expat openSUSE Tumbleweed 2.2.0-3.1

opensuse advisories openSUSE-SU-2024:10077-1

  • expat Alpine 3.4, Alpine 3.3, Alpine 3.2 2.2.0-r0

alpine advisories ALPINE-CVE-2016-5300

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2016-5300 updated cvss 4.3

expat: Little entropy used for hash initialization

  • Red Hat Enterprise Linux 5 expat, xmlrpc-c Red Hat Enterprise Linux 6 expat Red Hat Enterprise Linux 7 expat Red Hat JBoss Enterprise Application Platform 6 expat Red Hat JBoss Enterprise Web Server 2 expat Red Hat JBoss Enterprise Web Server 3 expat
    affected: no fix planned “Will not fix”
  • Red Hat Directory Server 8 expat
    under investigation
  • Red Hat Enterprise Linux 5 firefox, xulrunner, thunderbird Red Hat Enterprise Linux 6 firefox, xulrunner, thunderbird, compat-expat1 Red Hat Enterprise Linux 7 firefox, xulrunner, thunderbird Red Hat JBoss Core Services expat
    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

Exploit prediction

6.54% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 7.8 AV:N/AC:L/Au:N/C:N/I:N/A:C

Classification

Weakness
  • CWE-399 Resource Management Errors

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.