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FreeBSD-EN-26:18.tzdata Errata Notice
The FreeBSD Project
Topic: Timezone database information update
Category: contrib
Module: zoneinfo
Announced: 2026-07-29
Affects: All supported versions of FreeBSD.
Corrected: 2026-07-11 09:48:44 UTC (stable/15, 15.1-STABLE)
2026-07-29 17:50:24 UTC (releng/15.1, 15.1-RELEASE-p2)
2026-07-29 17:50:00 UTC (releng/15.0, 15.0-RELEASE-p12)
2026-07-11 09:52:47 UTC (stable/14, 14.4-STABLE)
2026-07-29 17:49:33 UTC (releng/14.4, 14.4-RELEASE-p8)
For general information regarding FreeBSD Errata Notices and Security
Advisories, including descriptions of the fields above, security branches,
and the following sections, please visit .
I. Background
The IANA Time Zone Database (often called tz or zoneinfo) contains code and
data that represent the history of local time for many representative
locations around the globe. It is updated periodically to reflect changes
made by political bodies to time zone boundaries, UTC offsets, and
daylight-saving rules.
FreeBSD releases install the IANA Time Zone Database in /usr/share/zoneinfo.
The tzsetup(8) utility allows the user to specify the default local time
zone. Based on the selected time zone, tzsetup(8) copies one of the files
from /usr/share/zoneinfo to /etc/localtime. A time zone may also be selected
for an individual process by setting its TZ environment variable to a desired
time zone name.
II. Problem Description
Several changes to future and past timestamps have been recorded in the IANA
Time Zone Database after previous FreeBSD releases were released. This
affects many users in different parts of the world. Because of these
changes, the data in the zoneinfo files need to be updated. If the local
timezone on the running system is affected, tzsetup(8) needs to be run to
update /etc/localtime.
III. Impact
An incorrect time will be displayed on a system configured to use one of the
affected time zones if the /usr/share/zoneinfo and /etc/localtime files are
not updated, and all applications on the system that rely on the system time,
such as cron(8) and syslog(8), will be affected.
IV. Workaround
The system administrator can install an updated version of the IANA Time Zone
Database from the misc/zoneinfo port and run tzsetup(8).
Applications that store and display times in Coordinated Universal Time (UTC)
are not affected.
V. Solution
Upgrade your system to a supported FreeBSD stable or release / security
branch (releng) dated after the correction date.
Please note that some third party software, for instance PHP, Ruby, Java,
Perl and Python, may be using different zoneinfo data sources, in such cases
this software must be updated separately. Software packages that are
installed via binary packages can be upgraded by executing 'pkg upgrade'.
Following the instructions in this Errata Notice will only update the IANA
Time Zone Database installed in /usr/share/zoneinfo.
Perform one of the following:
1) To update your system installed from base system packages:
Systems running a 15.0-RELEASE or later version of FreeBSD on the amd64 or
arm64 platforms, which were installed using base system packages, can be
updated via the pkg(8) utility:
# pkg upgrade -r FreeBSD-base
2) To update your system installed from binary distribution sets:
Systems running a RELEASE version of FreeBSD on the amd64 or arm64 platforms
which were not installed using base system packages can be updated via the
freebsd-update(8) utility:
# freebsd-update fetch
# freebsd-update install
3) To update your system via a source code patch:
The following patches have been verified to apply to the applicable
FreeBSD release branches.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
# fetch https://security.FreeBSD.org/patches/EN-26:18/tzdata-2026c.patch
# fetch https://security.FreeBSD.org/patches/EN-26:18/tzdata-2026c.patch.asc
# gpg --verify tzdata-2026c.patch.asc
b) Apply the patch. Execute the following commands as root:
# cd /usr/src
# patch -E -p0 < /path/to/patch
c) Recompile the operating system using buildworld and installworld as
described in .
Restart all the affected applications and daemons, or reboot the system.
VI. Correction details
This issue is corrected as of the corresponding Git commit hash in the
following stable and release branches:
Branch/path Hash Revision
- -------------------------------------------------------------------------
stable/15/ 6470095eaa17 stable/15-n284437
releng/15.1/ 3be83b93661d releng/15.1-n283583
releng/15.0/ 8dd31fbcc50f releng/15.0-n281087
stable/14/ 819af80de8e8 stable/14-n274491
releng/14.4/ 7a227adc1ac6 releng/14.4-n273748
- -------------------------------------------------------------------------
Run the following command to see which files were modified by a
particular commit:
# git show --stat
Or visit the following URL, replacing NNNNNN with the hash:
To determine the commit count in a working tree (for comparison against
nNNNNNN in the table above), run:
# git rev-list --count --first-parent HEAD
VII. References
The latest revision of this advisory is available at
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