Sensiolabs Symfony up to 5.4.55/6.4.49/7.4.22/8.1.10 DataUriNormalizer UploadedFile::isValid deserialization

Summaryinfo

A vulnerability marked as critical has been reported in Sensiolabs Symfony up to 5.4.55/6.4.49/7.4.22/8.1.10. Affected by this vulnerability is the function UploadedFile::isValid of the component DataUriNormalizer. The manipulation leads to deserialization. This vulnerability is documented as CVE-2026-118515. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Sensiolabs Symfony up to 5.4.55/6.4.49/7.4.22/8.1.10. It has been rated as critical. This issue affects the function UploadedFile::isValid of the component DataUriNormalizer. The manipulation with an unknown input leads to a deserialization vulnerability. Using CWE to declare the problem leads to CWE-502. The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-118515 since 10/28/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 5.4.56, 6.4.50, 7.4.23 or 8.1.11 eliminates this vulnerability.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Programming Tool Software

Vendor

• Sensiolabs

Name

• Symfony

Version

• 5.4.0
• 5.4.1
• 5.4.2
• 5.4.3
• 5.4.4
• 5.4.5
• 5.4.6
• 5.4.7
• 5.4.8
• 5.4.9
• 5.4.10
• 5.4.11
• 5.4.12
• 5.4.13
• 5.4.14
• 5.4.15
• 5.4.16
• 5.4.17
• 5.4.18
• 5.4.19
• 5.4.20
• 5.4.21
• 5.4.22
• 5.4.23
• 5.4.24
• 5.4.25
• 5.4.26
• 5.4.27
• 5.4.28
• 5.4.29
• 5.4.30
• 5.4.31
• 5.4.32
• 5.4.33
• 5.4.34
• 5.4.35
• 5.4.36
• 5.4.37
• 5.4.38
• 5.4.39
• 5.4.40
• 5.4.41
• 5.4.42
• 5.4.43
• 5.4.44
• 5.4.45
• 5.4.46
• 5.4.47
• 5.4.48
• 5.4.49
• 5.4.50
• 5.4.51
• 5.4.52
• 5.4.53
• 5.4.54
• 5.4.55
• 6.4.0
• 6.4.1
• 6.4.2
• 6.4.3
• 6.4.4
• 6.4.5
• 6.4.6
• 6.4.7
• 6.4.8
• 6.4.9
• 6.4.10
• 6.4.11
• 6.4.12
• 6.4.13
• 6.4.14
• 6.4.15
• 6.4.16
• 6.4.17
• 6.4.18
• 6.4.19
• 6.4.20
• 6.4.21
• 6.4.22
• 6.4.23
• 6.4.24
• 6.4.25
• 6.4.26
• 6.4.27
• 6.4.28
• 6.4.29
• 6.4.30
• 6.4.31
• 6.4.32
• 6.4.33
• 6.4.34
• 6.4.35
• 6.4.36
• 6.4.37
• 6.4.38
• 6.4.39
• 6.4.40
• 6.4.41
• 6.4.42
• 6.4.43
• 6.4.44
• 6.4.45
• 6.4.46
• 6.4.47
• 6.4.48
• 6.4.49
• 7.4.0
• 7.4.1
• 7.4.2
• 7.4.3
• 7.4.4
• 7.4.5
• 7.4.6
• 7.4.7
• 7.4.8
• 7.4.9
• 7.4.10
• 7.4.11
• 7.4.12
• 7.4.13
• 7.4.14
• 7.4.15
• 7.4.16
• 7.4.17
• 7.4.18
• 7.4.19
• 7.4.20
• 7.4.21
• 7.4.22
• 8.1.0
• 8.1.1
• 8.1.2
• 8.1.3
• 8.1.4
• 8.1.5
• 8.1.6
• 8.1.7
• 8.1.8
• 8.1.9
• 8.1.10

License

• open-source

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion