Symfony: DataUriNormalizer Opens Data URIs With a Non-Lowercase Scheme as Local Files, Letting a Client Read Any Server File
Summary
| CVE | CVE-2026-121623 |
|---|---|
| State | PUBLISHED |
| Assigner | Checkmarx |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-06 16:17:52 UTC |
| Updated | 2026-11-06 21:40:43 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 8.2 HIGH from 596c5446-0ce5-4ba2-aa66-48b3b757a647
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-22 | CWE-73 | CWE-73 CWE-73 External control of file name or path | CWE-22 CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 596c5446-0ce5-4ba2-aa66-48b3b757a647 | Secondary | 8.2 | HIGH | 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/E:X/C... |
| 4.0 | CNA | CVSS | 8.2 | HIGH | 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 |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
PresentPrivileges Required
NoneUser Interaction
NoneConfidentiality
HighIntegrity
NoneAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Sensiolabs | Symfony | affected 5.4.56 git | Not specified |
| CNA | Sensiolabs | Symfony | affected 6.0.0 6.4.50 git | Not specified |
| CNA | Sensiolabs | Symfony | affected 7.0.0 7.4.23 git | Not specified |
| CNA | Sensiolabs | Symfony | affected 8.0.0 8.1.11 git | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/symfony/symfony/security/advisories/GHSA-pxj9-jh84-vhm5 | 596c5446-0ce5-4ba2-aa66-48b3b757a647 | github.com | |
| github.com/symfony/symfony/commit/a0c551861ac23f888dfe6d1157ca78f4e220f3b7 | 596c5446-0ce5-4ba2-aa66-48b3b757a647 | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Nicolas Grekas (en)
There are currently no legacy QID mappings associated with this CVE.