Vulnerabilities

Vulnerability · CVE-2026-118515

Symfony: The Serializer Builds UploadedFile Objects From Request Data, Letting a Client Point an Upload at Any Server File

Published Nov 6, 2026 · catalog updated Nov 7, 2026 · Symfony: The Serializer Builds

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-118515. EPSS is 0.58%. Act only if a listed version of Symfony: The Serializer Builds is installed.

Severity

High8.4

Known exploitation

Not in CISA/VulnCheck KEV

EPSS

0.58%

Remediation

Advisory link

Affected products

Debian:12 symfony · Debian:13 symfony · Debian:14 symfony · vendor sensiolabs symfony

The Symfony Serializer component DataUriNormalizer handles only the exact types SplFileInfo, SplFileObject, and File, so for a property typed with a subclass such as UploadedFile, ObjectNormalizer instantiates the object through its constructor from attacker-controlled data, including the file path. This allows an arbitrary file on the server to be treated as an uploaded file in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11. A request body such as {"image": {"path": "/path/to/project/.env.local", "originalName": "a.png", "test": true}} makes the application handle any file on the server as an upload, without the file being sent. With test: true, UploadedFile::isValid() skips is_uploaded_file() and move() falls back to rename(). Assert\File does not prevent this because it validates the file at the attacker-chosen path, which exists on the server. Any code that deserializes untrusted data into a type that holds such a property is affected. That includes #[MapRequestPayload] on a DTO with an UploadedFile property, which is how uploads are mapped in Symfony 8.1; a single unauthenticated request with a JSON or form body is enough. Depending on what the application does with the upload, this can expose any file readable by PHP (for instance, when uploads are stored and served back), move any such file when move() is called, and reveal whether a path exists. A serializer built without DataUriNormalizer ahead of the object normalizer is not protected by the fix; the serializer configured by FrameworkBundle is.