Drupal Core: Gadget Chain Could Turn an Unserialize Bug Into Code Execution

Published as "Drupal core allows Object Injection"

medium Drupal · Last reviewed Nov 8, 2026

CVE: CVE-2025-13081
GHSA: GHSA-m6vv-vcj8-w8m7
Packagist: PKSA-xj83-g6g8-41vf
Reported: Nov 18, 2025

Gives an attacker a path to run code on a Drupal site, but only if a separate flaw already lets them pass untrusted data to unserialize().

Affected and fixed versions

In drupal/core. Find the row for the version you run, and update to the release next to it.

If you run	Update to	Support
11.2.0 – 11.2.7	11.2.8
11.0.0 – 11.1.8	11.1.9
10.5.0 – 10.5.5	10.5.6

Show 1 older branch

8.0.0 – 10.4.8

10.4.9

Upgrade

Run the line for the branch you are on.

composer require drupal/core:^11.2.8
composer require drupal/core:^11.1.9
composer require drupal/core:^10.5.6

What this means

Drupal core contains a "gadget chain": existing methods an attacker could string together to run code on your server and read or change any data. It isn't a hole on its own. It only becomes one if your site has a separate flaw that passes untrusted data to PHP's unserialize() (turning stored text back into objects, known as deserialization). Drupal's advisory says there are no such known flaws in Drupal core.

Who is affected

Sites on drupal/core from 8.0.0 up to the fixed releases below. The chain matters only where custom code or a contributed module calls unserialize() on data a user can control, such as request input or cookies. Drupal rates the setup needed as uncommon and complex, and its risk score assumes administrator-level access. Sites that never unserialize untrusted input aren't exposed through this chain.

What to do

Update to the fixed release for your branch:

Drupal 10.4: update to 10.4.9
Drupal 10.5: update to 10.5.6
Drupal 11.1: update to 11.1.9
Drupal 11.2: update to 11.2.8

Drupal 11.0.x, 10.3.x and older no longer get security fixes, so move to a supported branch.

Reported by anzuukino.

Check your app with an agent

Paste this into a coding agent that can read your project, such as Claude Code, Codex or Amp. It checks your composer.lock against the versions above and tells you what to update, without changing anything.

Check whether the PHP project you have access to is affected by this security advisory, and tell me what to update. Do a read-only check: don't edit files, don't run composer update or composer require, and don't try to reproduce the flaw.

Advisory: Drupal Core: Gadget Chain Could Turn an Unserialize Bug Into Code Execution (CVE-2025-13081, GHSA-m6vv-vcj8-w8m7)
Details: https://phpnews.net/security/drupal/ghsa-m6vv-vcj8-w8m7

Affected versions, as Composer constraints:
- drupal/core: >=11.2.0,<11.2.8|>=11.0.0,<11.1.9|>=10.5.0,<10.5.6|>=8.0.0,<10.4.9

Fixed releases:
- 11.2.0 – 11.2.7: update to 11.2.8
- 11.0.0 – 11.1.8: update to 11.1.9
- 10.5.0 – 10.5.5: update to 10.5.6

1. Find every composer.lock in the project outside vendor/ (a monorepo can have one per app) and read the installed version of each package above. Packages installed as dependencies of other packages count too.
2. Compare each installed version with its constraint: "|" separates alternative ranges, and "," means both bounds apply.
3. For each affected install, read "What this means" at https://phpnews.net/security/drupal/ghsa-m6vv-vcj8-w8m7 and check whether the project meets the conditions it describes (a feature in use, a config value, a driver). Say which conditions you could check and which you couldn't.
4. Report a table: lock file | package | installed version | affected (yes, no or unknown) | conditions met (yes, no or unknown) | update to | evidence. For each affected package, give the command that would fix it, without running it: composer update <package> --with-dependencies when it is only installed as a dependency of another package, or composer require with the fixed version when composer.json requires it directly. If the installed version is on a branch with no fixed release listed, say it needs a move to a newer branch.

Sources

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