The Symfony Serializer component DataUriNormalizer::denormalize() matches the data: scheme with a case-sensitive regular expression, allowing a value with an uppercase scheme, such as DATA:,/../../../etc/passwd, to bypass it, resulting in Arbitrary Local File Read through Path Traversal 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 value whose scheme is not lowercase data: are treated as a local file path and opened instead of being decoded as inline data, so the resulting File, \SplFileInfo, or \SplFileObject points at a file on the server, which the application then handles as the uploaded content.

Any endpoint that deserializes untrusted input into one of these types is affected. FrameworkBundle registers DataUriNormalizer ahead of ObjectNormalizer by default. A single request with a crafted DATA: value is enough to read arbitrary local files that the application can access, with no authentication needed if the endpoint is public.
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History

Fri, 06 Nov 2026 17:30:00 +0000

Type Values Removed Values Added
First Time appeared Sensiolabs
Sensiolabs symfony
Vendors & Products Sensiolabs
Sensiolabs symfony

Fri, 06 Nov 2026 16:15:00 +0000

Type Values Removed Values Added
Description The Symfony Serializer component DataUriNormalizer::denormalize() matches the data: scheme with a case-sensitive regular expression, allowing a value with an uppercase scheme, such as DATA:,/../../../etc/passwd, to bypass it, resulting in Arbitrary Local File Read through Path Traversal 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 value whose scheme is not lowercase data: are treated as a local file path and opened instead of being decoded as inline data, so the resulting File, \SplFileInfo, or \SplFileObject points at a file on the server, which the application then handles as the uploaded content. Any endpoint that deserializes untrusted input into one of these types is affected. FrameworkBundle registers DataUriNormalizer ahead of ObjectNormalizer by default. A single request with a crafted DATA: value is enough to read arbitrary local files that the application can access, with no authentication needed if the endpoint is public.
Title Symfony: DataUriNormalizer Opens Data URIs With a Non-Lowercase Scheme as Local Files, Letting a Client Read Any Server File
Weaknesses CWE-22
CWE-73
References
Metrics cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Checkmarx

Published:

Updated: 2026-11-06T16:08:32.425Z

Reserved: 2026-11-03T16:50:15.733Z

Link: CVE-2026-121623

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-06T16:17:52.780

Modified: 2026-11-06T16:17:52.780

Link: CVE-2026-121623

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-11-06T17:45:06Z

Weaknesses