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CVE-2016-9843

33
FAUCET Score

CVE-2016-9843 describes a critical vulnerability in the crc32_big function within zlib 1.2.8, potentially allowing context-dependent attackers to achieve significant impact through big-endian CRC calculations. This affects numerous products including Apple, Canonical, Debian, MariaDB, Node.js, and Red Hat. With a CVSS score of 9.8 (CRITICAL), this vulnerability is remotely exploitable with low attack complexity, potentially leading to high confidentiality, integrity, and availability impacts. Despite its high severity, there is no evidence of active exploitation, no known public exploit code (Metasploit, Nuclei, ExploitDB), and minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 1.2.0, < 1.2.9CPE matchmatch criteria
cpe:2.3:a:zlib:zlib:*:*:*:*:*:*:*:*
42.1CPE matchmatch criteria
cpe:2.3:o:opensuse:leap:42.1:*:*:*:*:*:*:*
42.2CPE matchmatch criteria
cpe:2.3:o:opensuse:leap:42.2:*:*:*:*:*:*:*
13.2CPE matchmatch criteria
cpe:2.3:o:opensuse:opensuse:13.2:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
5.77%
Probability of exploitation in next 30 days
EPSS Percentile
92.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0577 is in the 87th percentile among its peer group of 36,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (16)

microsoftpatch availablevia msrc
Product: 16826-17084Fixed in: 1.3.8-1
microsoftpatch availablevia msrc
Product: 16826-16817Fixed in: 1.3.8-1
microsoftpatch availablevia msrc
Product: azl3 fltk 1.3.8-1 on Azure Linux 3.0Fixed in: 1.3.8-1
redhatpatch availablevia redhat_api
Product: Oracle Java for Red Hat Enterprise Linux 6Fixed in: java-1.6.0-sun-1:1.6.0.171-1jpp.4.el6
View patch
redhatpatch availablevia redhat_api
Product: Oracle Java for Red Hat Enterprise Linux 7Fixed in: java-1.8.0-oracle-1:1.8.0.151-1jpp.5.el7
View patch
redhatpatch availablevia redhat_api
Product: Oracle Java for Red Hat Enterprise Linux 7Fixed in: java-1.7.0-oracle-1:1.7.0.161-1jpp.4.el7
View patch
redhatpatch availablevia redhat_api
Product: Oracle Java for Red Hat Enterprise Linux 7Fixed in: java-1.6.0-sun-1:1.6.0.171-1jpp.4.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6 SupplementaryFixed in: java-1.8.0-ibm-1:1.8.0.4.5-1jpp.1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6 SupplementaryFixed in: java-1.7.1-ibm-1:1.7.1.4.5-1jpp.2.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6 SupplementaryFixed in: java-1.6.0-ibm-1:1.6.0.16.45-1jpp.1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7 SupplementaryFixed in: java-1.8.0-ibm-1:1.8.0.4.5-1jpp.1.el7_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7 SupplementaryFixed in: java-1.7.1-ibm-1:1.7.1.4.5-1jpp.1.el7_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Satellite 5.8Fixed in: java-1.8.0-ibm-1:1.8.0.5.5-1jpp.1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Satellite 5.8 ELSFixed in: java-1.8.0-ibm-1:1.8.0.5.5-1jpp.1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Oracle Java for Red Hat Enterprise Linux 6Fixed in: java-1.8.0-oracle-1:1.8.0.151-1jpp.1.el6
View patch
redhatpatch availablevia redhat_api
Product: Oracle Java for Red Hat Enterprise Linux 6Fixed in: java-1.7.0-oracle-1:1.7.0.161-1jpp.3.el6
View patch

Vendor Advisories (2)

microsoft2017-May/CVE-2016-9843Critical

The crc32_big function in crc32.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation.

May 9, 2017
redhatCVE-2016-9843Low

zlib: Big-endian out-of-bounds pointer

Sep 29, 2016

References

lists.opensuse.org / opensuse-updates/2016-12/msg00127.html
lists.opensuse.org / opensuse-updates/2017-01/msg00050.html
lists.opensuse.org / opensuse-updates/2017-01/msg00053.html
access.redhat.com / errata/RHSA-2017:1220
access.redhat.com / errata/RHSA-2017:1221
access.redhat.com / errata/RHSA-2017:1222
access.redhat.com / errata/RHSA-2017:2999
access.redhat.com / errata/RHSA-2017:3046
access.redhat.com / errata/RHSA-2017:3047
access.redhat.com / errata/RHSA-2017:3453
bugzilla.redhat.com / show_bug.cgi
github.com / madler/zlib/commit/d1d577490c15a0c6862473d7576352a9f18ef811
lists.debian.org / debian-lts-announce/2019/03/msg00027.html
lists.debian.org / debian-lts-announce/2020/01/msg00030.html
security.gentoo.org / glsa/201701-56
security.gentoo.org / glsa/202007-54
security.netapp.com / advisory/ntap-20181018-0002
support.apple.com / HT208112
support.apple.com / HT208113
support.apple.com / HT208115
support.apple.com / HT208144
usn.ubuntu.com / 4246-1
usn.ubuntu.com / 4292-1
wiki.mozilla.org / images/0/09/Zlib-report.pdf
wiki.mozilla.org / MOSS/Secure_Open_Source/Completed
oracle.com / security-alerts/cpujul2020.html
openwall.com / lists/oss-security/2016/12/05/21
oracle.com / technetwork/security-advisory/cpujul2018-4258247.html
oracle.com / technetwork/security-advisory/cpuoct2017-3236626.html
oracle.com / technetwork/security-advisory/cpuoct2018-4428296.html
securityfocus.com / bid/95131
securitytracker.com / id/1039427
securitytracker.com / id/1041888