Skip to content
Fencer Vulns
medium 6.3

CVE-2023-51447 json

Decidim vulnerable to cross-site scripting (XSS) in the dynamic file uploads

published 2024-02-20 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-0603 , GHSA-9w99-78rj-hmxq

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

Decidim is a participatory democracy framework. Starting in version 0.27.0 and prior to versions 0.27.5 and 0.28.0, the dynamic file upload feature is subject to potential cross-site scripting attacks in case the attacker manages to modify the file names of the records being uploaded to the server. This appears in sections where the user controls the file upload dialogs themselves and has the technical knowledge to change the file names through the dynamic upload endpoint. Therefore I believe it would require the attacker to control the whole session of the particular user but in any case, this needs to be fixed. Successful exploit of this vulnerability would require the user to have successfully uploaded a file blob to the server with a malicious file name and then have the possibility to direct the other user to the edit page of the record where the attachment is attached. The users are able to craft the direct upload requests themselves controlling the file name that gets stored to the database. The attacker is able to change the filename e.g. to `<svg onload=alert('XSS')>` if they know how to craft these requests themselves. And then enter the returned blob ID to the form inputs manually by modifying the edit page source. Versions 0.27.5 and 0.28.0 contain a patch for this issue. As a workaround, disable dynamic uploads for the instance, e.g. from proposals.

Patch / fix

  • rubygems decidim 0.27.5
  • rubygems decidim-core 0.27.5
  • decidim decidim 0.27.5

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N
GitHub 3.1 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
rubygems decidim
>=0.27.0, <0.27.5
0.27.5
rubygems decidim-core
>=0.27.0, <0.27.5
0.27.5

Affected products

  • decidim decidim

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.