Symfony Filesystem: Crafted Paths Can Escape Their Base Directory

Published as "Filesystem Path Treats Any Prefix Before "://" as a Root, Letting Paths Escape Their Base Directory"

high Symfony Symfony components · Last reviewed Nov 5, 2026

CVE: No CVE assigned
GHSA: None
Packagist: PKSA-g499-cm4q-v35y
Reported: Nov 4, 2026

Lets an attacker read or write files outside an allowed folder in apps that check user paths with Path, and lets packages write outside assets/vendor.

Affected and fixed versions

In 2 packages: symfony/filesystem and symfony/symfony. Find the row for the version you run, and update to the release next to it.

If you run	Update to	Support
8.1.0 – 8.1.10	8.1.11	Supported
7.4.0 – 7.4.22	7.4.23	Supported
6.4.0 – 6.4.49	6.4.50	Supported
5.4.0 – 5.4.55	5.4.56	Supported

Show 9 older branches, no longer supported

8.0.0 – 8.0.x	8.1.11
7.0.0 – 7.0.x	7.4.23
7.1.0 – 7.1.x	7.4.23
7.2.0 – 7.2.x	7.4.23
7.3.0 – 7.3.x	7.4.23
6.0.0 – 6.0.x	6.4.50
6.1.0 – 6.1.x	6.4.50
6.2.0 – 6.2.x	6.4.50
6.3.0 – 6.3.x	6.4.50

Upgrade

Run the line for the branch you are on. 1 other package listed above is affected too; update it the same way.

composer require symfony/filesystem:^8.1.11
composer require symfony/filesystem:^7.4.23
composer require symfony/filesystem:^6.4.50
composer require symfony/filesystem:^5.4.56

What this means

An attacker who controls part of a file path can make it point outside the folder your app meant to allow, so your app reads or writes a file somewhere else on the server. Symfony's Path class treated any text before :// as the start of a path, and didn't resolve the .. segments that came after it.

Who is affected

Apps on symfony/filesystem (also part of symfony/symfony) that build a path from user input and check it with Path::isBasePath() or Path::canonicalize() before opening it. Path::join(), Path::makeAbsolute() and Path::makeRelative() are affected the same way.

The Symfony advisory also names AssetMapper on 6.4 and later. A malicious or compromised package can make importmap:require or importmap:install write a file of its choice outside assets/vendor.

Apps that never pass untrusted paths to Path, and don't install untrusted packages with AssetMapper, aren't exposed.

What to do

Update to 5.4.56, 6.4.50, 7.4.23 or 8.1.11. If you're on 8.0, update to 8.1.11. The fix only treats a prefix as a scheme when PHP would. Real stream wrappers such as phar:// and file:// keep working.

Reported and fixed by Nicolas Grekas.

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: Symfony Filesystem: Crafted Paths Can Escape Their Base Directory (PKSA-FZ6M-R4PD-17C9)
Details: https://phpnews.net/security/symfony/pksa-fz6m-r4pd-17c9

Affected versions, as Composer constraints:
- symfony/filesystem, symfony/symfony: >=5.4.0,<5.4.56|>=6.0.0,<6.1.0|>=6.1.0,<6.2.0|>=6.2.0,<6.3.0|>=6.3.0,<6.4.0|>=6.4.0,<6.4.50|>=7.0.0,<7.1.0|>=7.1.0,<7.2.0|>=7.2.0,<7.3.0|>=7.3.0,<7.4.0|>=7.4.0,<7.4.23|>=8.0.0,<8.1.0|>=8.1.0,<8.1.11

Fixed releases on branches that still get security fixes:
- 8.1.0 – 8.1.10: update to 8.1.11
- 7.4.0 – 7.4.22: update to 7.4.23
- 6.4.0 – 6.4.49: update to 6.4.50
- 5.4.0 – 5.4.55: update to 5.4.56

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/symfony/pksa-fz6m-r4pd-17c9 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

The project's advisory →

← All Symfony advisories