CVE-2026-120326 · Package
NO FIX YET · SEE WHAT TO DO
Vaadin Flow's DownloadEvent.setFileName and inline methods do not escape the download file name in the Content-Disposition header. An attacker who controls a file name the application serves can add a filename* parameter, so browsers save the file under a name and extension the attacker chooses.
first public Nov 10, 2026 · 1 source
Could this affect your app?
Free first check from your website. Connect your repo for the full answer.
Applications built with Vaadin Flow that pass an untrusted file name to DownloadEvent.setFileName or the inline method, for example when re-serving an uploaded file under its original name, are exposed. Versions below 24.8 are not affected because the API does not exist there, and applications that only serve files under names they generate themselves are not meaningfully exposed.
Not affected if fixed-version, no-download-api, server-generated-file-names
Who cares file-download, java, vaadin, vaadin-flow
com.vaadin dependencies.DownloadEvent.setFileName( or inline( that pass user-supplied file names.24.8.0 to 24.8.17, 24.9.0 to 24.9.25, 24.10.0 to 24.10.13, to , to , to , to .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.
Check it with your coding agent
It reads this page and tells you if your code is affected.
Are you affected?
Ask from here. InfraStack checks the affected versions against your stack and answers in your inbox.
InfraStack checks the affected versions against your stack and answers in Slack, with the evidence and the fix.
25.0.025.0.1325.1.025.1.1325.2.025.2.1225.3.025.3.424.9.2624.10.1425.2.1325.3.5This page as .md · .json · 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
NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.