CVE-2026-55878: symfony/ux-toolkit Path Traversal Vulnerability
HIGHCVE-2026-55878 is a HIGH (CVSS 7.8) path traversal vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting symfony/ux-toolkit libraries in the Packagist ecosystem. The issue involves path traversal allows arbitrary file write and read via crafted recipe manifest. Remediation is available by upgrading affected packages to version 2.36.1, 3.2.0.
CVE-2026-55878 at a Glance
Security Impact
CVSS: 7.8
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).
How to Fix CVE-2026-55878
To remediate this vulnerability, upgrade all affected symfony/ux-toolkit dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade symfony/ux-toolkit to 2.36.1Upgrade symfony/ux-toolkit to 3.2.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for symfony/ux-toolkitHow to Check if You Are Affected
To determine whether your application is affected by CVE-2026-55878, inspect your project dependencies for symfony/ux-toolkit:
inspect dependencies for symfony/ux-toolkitAnalyze the terminal output to locate any version of symfony/ux-toolkit in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.36.1), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In symfony/ux-toolkit, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-55878 Affected symfony/ux-toolkit Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
symfony/ux-toolkit
|
Packagist |
≥ 2.32.0
< 2.36.1
|
2.36.1
|
|
symfony/ux-toolkit
|
Packagist |
≥ 3.0.0
< 3.2.0
|
3.2.0
|
References
Frequently Asked Questions
What is CVE-2026-55878?
Which symfony/ux-toolkit versions are affected?
What version fixes CVE-2026-55878?
Is symfony/ux-toolkit affected?
What is the CVSS score of CVE-2026-55878?
What CWE is associated with CVE-2026-55878?
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Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-p9xj-fpr2-jf2q",
"modified" : "2026-06-19T21:42:18Z",
"published" : "2026-06-19T21:42:18Z",
"aliases" : [ "CVE-2026-55878" ],
"summary" : "symfony/ux-toolkit: Path Traversal Allows Arbitrary File Write and Read via Crafted Recipe Manifest",
"details" : "### Description\nThe `ux:install` console command installs files from a recipe kit by copying paths listed in a `copy-files` map. The only guard against malicious paths was `Path::isRelative()`, which returns `true` for paths like `../../../etc`. `Path::join()` then resolves the `..` segments without complaint, so the final path can escape the intended directory entirely. A crafted or compromised kit can therefore write attacker-controlled content to arbitrary locations on the developer's machine or CI runner.\n\nBecause the copy operation creates missing parent directories and can overwrite existing files silently (with `--force` or in non-interactive environments), an attacker who controls a kit can overwrite files such as controllers, git hooks, or `.env` to achieve code execution. The source side of `copy-files` is symmetrically affected, enabling local file reads outside the recipe directory.\n\n### Resolution\n\nThe fix introduces an `Assert::pathDoesNotEscapeDirectory()` helper that rejects any `copy-files` source or destination path containing a `..` segment, regardless of whether `/` or `\\` is used as the separator. This check is enforced in both `RecipeManifest` (which also guards the source Finder) and `File`. As a last line of defense, the installer re-verifies the fully resolved paths with `Path::isBasePath()` immediately before each filesystem read and write.\n\n### Credits\n\nSymfony would like to thank Pascal Cescon for reporting the issue and Hugo Alliaume for providing the fix.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Packagist",
"name" : "symfony/ux-toolkit"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.32.0"
}, {
"fixed" : "2.36.1"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Packagist",
"name" : "symfony/ux-toolkit"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "3.0.0"
}, {
"fixed" : "3.2.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/symfony/ux/security/advisories/GHSA-p9xj-fpr2-jf2q"
}, {
"type" : "WEB",
"url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/ux-toolkit/CVE-2026-55878.yaml"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/symfony/ux"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-22" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-06-19T21:42:18Z",
"nvd_published_at" : null
}
}