CVE-2016-9843: Critical severity Apple tvOS vulnerability

Published Dec 7, 2016
·
Updated

Last updated 14 January 2026

Other sources

The crc32big 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.

— Launchpad

There was a small optimization for PowerPCs to pre-increment a pointer when accessing a word, instead of post-incrementing. This required prefacing the loop with a decrement of the pointer, possibly pointing before the object passed. This is not compliant with the C standard, for which decrementing a pointer before its allocated memory is undefined. When tested on a modern PowerPC with a modern compiler, the optimization no longer has any effect.

External References:

https://wiki.mozilla.org/images/0/09/Zlib-report.pdf https://docs.google.com/document/d/10i1KZS5so8xDqH2rplRa2xet0tyTvvJlLbQQmZIUIKE/edit#heading=h.t13tvnx4loq7

Upstream patch:

https://github.com/madler/zlib/commit/d1d577490c15a0c6862473d7576352a9f18ef811

CVE assignment:

http://seclists.org/oss-sec/2016/q4/602

— Red Hat

zlib. Multiple issues were addressed by updating to version 1.2.11.

Credit

CVE-2016-9840, CVE-2016-9841, CVE-2016-9842, CVE-2016-9843, CVE-2016-9840, CVE-2016-9841, CVE-2016-9842, CVE-2016-9843

Affected Software

53 affected componentsFixes available
redhat/zlib<1.2.9
1.2.9
Apple tvOS<11
11
Apple macOS High Sierra<10.13
10.13
Apple WatchOS<4
4
Apple iOS<11
11
zlib zlib>=1.2.0<1.2.9
openSUSE Leap=42.1
openSUSE Leap=42.2
openSUSE openSUSE=13.2
Debian Debian Linux=8.0
Canonical Ubuntu Linux=16.04
Canonical Ubuntu Linux=18.04
Oracle Database Server=18c
Oracle JDK=1.6.0-update161
Oracle JDK=1.7.0-update151
Oracle JDK=1.8.0-update144
Oracle JRE=1.6.0-update161
Oracle JRE=1.7.0-update151
Oracle JRE=1.8.0-update144
Oracle MySQL>=5.5.0<=5.5.61
Oracle MySQL>=5.6.0<=5.6.41
Oracle MySQL>=5.7.0<=5.7.23
Oracle MySQL>=8.0.0<=8.0.12
redhat Satellite=5.8
redhat Enterprise Linux Desktop=6.0
redhat Enterprise Linux Desktop=7.0
redhat Enterprise Linux Eus=7.4
redhat Enterprise Linux Eus=7.5
redhat Enterprise Linux Server=6.0
redhat Enterprise Linux Server=7.0
redhat Enterprise Linux Workstation=6.0
redhat Enterprise Linux Workstation=7.0
Apple iPhone OS<11
Apple iOS and macOS>=10.0.0<10.13.0
Apple tvOS<11.0
Apple WatchOS<4
NetApp Active Iq Unified Manager Windows>=7.3
NetApp Active Iq Unified Manager Vmware Vsphere>=9.5
NetApp OnCommand Insight
NetApp OnCommand Workflow Automation
NetApp Snapcenter
MariaDB MariaDB>=5.5.0<5.5.62
MariaDB MariaDB>=10.0.0<10.0.37
MariaDB MariaDB>=10.1.0<10.1.37
MariaDB MariaDB>=10.2.0<10.2.19
MariaDB MariaDB>=10.3.0<10.3.11
Nodejs Node.js>=4.0.0<=4.1.2
Nodejs Node.js>=4.2.0<4.8.2
Nodejs Node.js>=6.0.0<=6.8.1
Nodejs Node.js>=6.9.0<6.10.2
Nodejs Node.js>=7.0.0<7.6.0
debian/rsync
3.2.3-4+deb11u13.2.3-4+deb11u43.2.7-1+deb12u63.2.7-1+deb12u53.4.1+ds1-5+deb13u43.4.1+ds1-5+deb13u33.4.4+ds1-1
debian/zlib
1:1.2.11.dfsg-2+deb11u21:1.2.13.dfsg-11:1.3.dfsg+really1.3.1-11:1.3.dfsg+really1.3.2-3

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/zlib to a version that resolves this vulnerability.

    Fixed in 1.2.9
  2. Upgrade

    Upgrade tvOS to a version that resolves this vulnerability.

    Fixed in 11
  3. Upgrade

    Upgrade macOS High Sierra to a version that resolves this vulnerability.

    Fixed in 10.13
  4. Upgrade

    Upgrade Apple iOS, iPadOS, and watchOS to a version that resolves this vulnerability.

    Fixed in 4
  5. Upgrade

    Upgrade Apple iOS and iPadOS to a version that resolves this vulnerability.

    Fixed in 11
  6. Upgrade

    Upgrade debian/rsync to a version that resolves this vulnerability.

    Fixed in 3.2.3-4+deb11u1Fixed in 3.2.3-4+deb11u4Fixed in 3.2.7-1+deb12u6Fixed in 3.2.7-1+deb12u5Fixed in 3.4.1+ds1-5+deb13u4Fixed in 3.4.1+ds1-5+deb13u3Fixed in 3.4.4+ds1-1
  7. Upgrade

    Upgrade debian/zlib to a version that resolves this vulnerability.

    Fixed in 1:1.2.11.dfsg-2+deb11u2Fixed in 1:1.2.13.dfsg-1Fixed in 1:1.3.dfsg+really1.3.1-1Fixed in 1:1.3.dfsg+really1.3.2-3
  8. Upgrade

    Upgrade zlib to a version that resolves this vulnerability.

    Fixed in 1.2.11
  9. Compensating control

    If you cannot upgrade zlib to 1.2.11 immediately, limit exposure by reducing where the vulnerable zlib functions are used on attacker-controlled inputs (e.g., avoid processing untrusted compressed data paths) until the update is applied.

Event History

May 23, 2017
CVE Published
via MITRE·03:56 AM
Data Sourced
via MITRE·03:56 AM
Description
Data Sourced
via NVD·04:29 AM
DescriptionSeverityAffected Software
Jan 11, 2024
Data Sourced
via Launchpad·10:23 PM
Description
Feb 19, 2026
Data Sourced
via Ubuntu·07:17 PM
RemedyDescriptionSeverityAffected Software
Jul 14, 2026
Data Sourced
via Debian·12:11 PM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

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Frequently Asked Questions

1

What is CVE-2016-9843?

CVE-2016-9843 is a vulnerability in zlib 1.2.8 that can allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation.

2

What is the severity of CVE-2016-9843?

The severity of CVE-2016-9843 is critical with a CVSS score of 9.8.

3

How can I fix CVE-2016-9843?

CVE-2016-9843 can be fixed by updating zlib to version 1.2.9 or later.

4

Where can I find more information about CVE-2016-9843?

You can find more information about CVE-2016-9843 at the following references: [link1], [link2], [link3].

Company

Resources

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