Single Content Sync security updates, in plain English

Single Content Sync

19,748 sites report using it · on drupal.org · 1 security update explained here

This module lets administrators export and import content between different websites.

Below is every security update for Single Content Sync that this site has covered, newest first. Each one says who could exploit it, whether it applies to your site, how urgent it is, and what to tell your developer. If your site uses this module and you are not sure which version, that is the first question to ask whoever looks after it.

Single Content Sync

Critical · 19,748 sites report using it · 2 security fixes · Week of 28 October 2026

2 security fixes in one update. Single Content Sync fixed 2 separate security bugs at once: 1 remote code execution, 1 external control of file name or path. One update covers all of them. The most serious, SA-CONTRIB-2026-275, is explained here and the full list is at the end of the card.

The module does not properly handle data from imported files. Someone could use a malicious import file to run harmful code and change or read any data on the site. They could not do this without the right to import content.

Who could do thisOnly someone with an administrator login.
Does it apply to youAn attacker has an account with the access right to import single content.
Has it been used in attacksNo sign of it.
How urgentDrupal rates this critical. Cyber Essentials expects a fix within 14 days. Do it this week.

Tell your developerUpdate Single Content Sync to 1.4.19.

For developers: what the fix changed

This release carries 2 security fixes. The summary below is for SA-CONTRIB-2026-275, the most serious of them.

The fix prevents untrusted data deserialization by unsetting the `block_serialized` configuration key for inline blocks in `src/Plugin/SingleContentSyncFieldProcessor/LayoutSection.php`.

Also in this release The release also introduces extensive validation for imported files, restricts remote downloads to trusted hosts, and adds an ImportFileManager service.

1.4.18 to 1.4.19 2 commits, 19 files including 5 tests.

.cspell.json +4 −1
README.md +26 −0
composer.json +1 −0
config/install/single_content_sync.settings.yml +2 −0
config/schema/single_content_sync.schema.yml +8 −0
single_content_sync.permissions.yml +1 −0
single_content_sync.post_update.php +16 −0
single_content_sync.services.yml +9 −0
src/ContentBatchImporter.php +1 −1
src/ContentImporter.php +23 −14
src/Form/ContentSyncConfigForm.php +38 −0
src/ImportFileManager.php +264 −0

Full diff, 1.4.18 to 1.4.19

The comparison is against the release immediately before the fix. If your site is on an older release, more will have changed.

All 2 security bugs this update fixes, worst first. Each link is the drupal.org notice for that one.

Critical · Remote code execution · SA-CONTRIB-2026-275
Critical · External control of file name or path · SA-CONTRIB-2026-274

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If I can help, I'll say so and suggest a call. If I can't, I'll tell you straight away rather than waste your time.

For context: I work mainly with UK membership bodies, charities and research organisations, and with the agencies that look after their websites. Not recruiters.

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