Unescaped Download File Name Allows Content-Disposition Parameter Injection in Vaadin Flow
Summary
| CVE | CVE-2026-120326 |
|---|---|
| State | PUBLISHED |
| Assigner | Vaadin |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-10 12:17:16 UTC |
| Updated | 2026-11-10 12:17:16 UTC |
| Description | DownloadEvent.setFileName(String) in Vaadin Flow writes the download file name into the Content-Disposition header without escaping it. When the name is pure US-ASCII the header is built as attachment; filename="<name>" with the name inserted verbatim, so a double quote in the name ends the quoted string early and the rest of the name is read by the browser as further header parameters. The inline(String) variant, present from Vaadin 25.0, builds the name the same way. An application that passes an untrusted file name to either method, for example when re-serving a file under the name it was uploaded with, lets an attacker add a filename* parameter. Browsers prefer filename* over filename, so the file is saved under a name and extension of the attacker's choosing, which defeats any file name or extension restriction the application enforces. The attacker cannot change the attachment or inline disposition itself and cannot split the header. Users of affected versions should apply the following mitigation or upgrade. Releases that have fixed this issue include: Product version Vaadin 24.8.0 - 24.8.17 Vaadin 24.9.0 - 24.9.25 Vaadin 24.10.0 - 24.10.13 Vaadin 25.0.0 - 25.0.13 Vaadin 25.1.0 - 25.1.13 Vaadin 25.2.0 - 25.2.12 Vaadin 25.3.0 - 25.3.4 Mitigation No fixed release on this line, upgrade to 24.9.26 or newer Upgrade to 24.9.26 Upgrade to 24.10.14 No fixed release on this line, upgrade to 25.2.13 or newer No fixed release on this line, upgrade to 25.2.13 or newer Upgrade to 25.2.13 Upgrade to 25.3.5 Vaadin versions below 24.8 are not affected: the DownloadEvent API does not exist in them. |
Risk And Classification
Primary CVSS: v4.0 4.8 MEDIUM from [email protected]
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/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-116 | CWE-116 CWE-116 Improper Encoding or Escaping of Output
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 4.8 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 4.8 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
NonePrivileges Required
LowUser Interaction
ActiveConfidentiality
NoneIntegrity
NoneAvailability
NoneSub Conf.
NoneSub Integrity
LowSub Availability
NoneCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/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 | Vaadin | Vaadin | affected 24.8.0 24.8.17 maven | Not specified |
| CNA | Vaadin | Vaadin | affected 24.9.0 24.9.26 maven | Not specified |
| CNA | Vaadin | Vaadin | affected 24.10.0 24.10.14 maven | Not specified |
| CNA | Vaadin | Vaadin | affected 25.0.0 25.0.13 maven | Not specified |
| CNA | Vaadin | Vaadin | affected 25.1.0 25.1.13 maven | Not specified |
| CNA | Vaadin | Vaadin | affected 25.2.0 25.2.13 maven | Not specified |
| CNA | Vaadin | Vaadin | affected 25.3.0 25.3.5 maven | Not specified |
| CNA | Vaadin | Vaadin-core | affected 24.8.0 24.8.17 maven | Not specified |
| CNA | Vaadin | Vaadin-core | affected 24.9.0 24.9.26 maven | Not specified |
| CNA | Vaadin | Vaadin-core | affected 24.10.0 24.10.14 maven | Not specified |
| CNA | Vaadin | Vaadin-core | affected 25.0.0 25.0.13 maven | Not specified |
| CNA | Vaadin | Vaadin-core | affected 25.1.0 25.1.13 maven | Not specified |
| CNA | Vaadin | Vaadin-core | affected 25.2.0 25.2.13 maven | Not specified |
| CNA | Vaadin | Vaadin-core | affected 25.3.0 25.3.5 maven | Not specified |
| CNA | Vaadin | Flow | affected 24.8.0 24.8.16 maven | Not specified |
| CNA | Vaadin | Flow | affected 24.9.0 24.9.31 maven | Not specified |
| CNA | Vaadin | Flow | affected 24.10.0 24.10.17 maven | Not specified |
| CNA | Vaadin | Flow | affected 25.0.0 25.0.15 maven | Not specified |
| CNA | Vaadin | Flow | affected 25.1.0 25.1.19 maven | Not specified |
| CNA | Vaadin | Flow | affected 25.2.0 25.2.16 maven | Not specified |
| CNA | Vaadin | Flow | affected 25.3.0 25.3.6 maven | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/vaadin/flow/pull/26704 | [email protected] | github.com | |
| vaadin.com/security/cve-2026-120326 | [email protected] | vaadin.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
Additional Advisory Data
Solutions
CNA: Users of affected versions should apply the following mitigation or upgrade.
Workarounds
CNA: Escape or reject double quotes, backslashes and control characters in any file name that does not come from the application itself before passing it to DownloadEvent.setFileName or DownloadEvent.inline.
There are currently no legacy QID mappings associated with this CVE.