Ubuntu alert USN-8706-1 (zlib)

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[USN-8706-1] zlib vulnerability
Date:
             
 
Tue, 01 Sep 2026 07:28:04 +0000
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<E1x1Iua-0004vn-MZ@lists.ubuntu.com>
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noreply+usn-bot@canonical.com
==========================================================================
Ubuntu Security Notice USN-8706-1
August 31, 2026

zlib vulnerability
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS

Summary:

zlib could be made to consume excessive CPU resources if it received
specially crafted input.

Software Description:
- zlib: Lossless data-compression library

Details:

It was discovered that zlib incorrectly handled negative length parameters
in CRC32 combine functions. An attacker could use this issue to cause a denial
of service via excessive CPU consumption.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
  lib32z1                         1:1.3.dfsg+really1.3.1-1ubuntu3.1
  lib32z1-dev                     1:1.3.dfsg+really1.3.1-1ubuntu3.1
  lib64z1                         1:1.3.dfsg+really1.3.1-1ubuntu3.1
  lib64z1-dev                     1:1.3.dfsg+really1.3.1-1ubuntu3.1
  libminizip-dev                  1:1.3.dfsg+really1.3.1-1ubuntu3.1
  libminizip1t64                  1:1.3.dfsg+really1.3.1-1ubuntu3.1
  libx32z1                        1:1.3.dfsg+really1.3.1-1ubuntu3.1
  libx32z1-dev                    1:1.3.dfsg+really1.3.1-1ubuntu3.1
  minizip                         1:1.3.dfsg+really1.3.1-1ubuntu3.1
  zlib1g                          1:1.3.dfsg+really1.3.1-1ubuntu3.1
  zlib1g-dev                      1:1.3.dfsg+really1.3.1-1ubuntu3.1

Ubuntu 24.04 LTS
  lib32z1                         1:1.3.dfsg-3.1ubuntu2.2
  lib32z1-dev                     1:1.3.dfsg-3.1ubuntu2.2
  lib64z1                         1:1.3.dfsg-3.1ubuntu2.2
  lib64z1-dev                     1:1.3.dfsg-3.1ubuntu2.2
  libminizip-dev                  1:1.3.dfsg-3.1ubuntu2.2
  libminizip1t64                  1:1.3.dfsg-3.1ubuntu2.2
  libx32z1                        1:1.3.dfsg-3.1ubuntu2.2
  libx32z1-dev                    1:1.3.dfsg-3.1ubuntu2.2
  minizip                         1:1.3.dfsg-3.1ubuntu2.2
  zlib1g                          1:1.3.dfsg-3.1ubuntu2.2
  zlib1g-dev                      1:1.3.dfsg-3.1ubuntu2.2

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-8706-1
  CVE-2026-27171

Package Information:
  https://launchpad.net/ubuntu/+source/zlib/1:1.3.dfsg+real...
  https://launchpad.net/ubuntu/+source/zlib/1:1.3.dfsg-3.1u...


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