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Fencer Vulns
low 3.3

CVE-2025-66548 json

Nextcloud Deck app allows to spoof file extensions by using RTLO characters

published 2025-12-05 11 mo ago modified 2026-10-15 24 d ago also EUVD-2025-201466

cvss
3.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits
0
none known

Summary

Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. Prior to 1.12.7, 1.14.4, and 1.15.1, file extension can be spoofed by using RTLO characters, tricking users into download files with a different extension than what is displayed. This vulnerability is fixed in 1.12.7, 1.14.4, and 1.15.1.

Patch / fix

  • nextcloud deck 1.12.7, 1.14.4, 1.15.1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
11 mo ago

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 3.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected products

  • nextcloud security-advisories

Classification

Weakness
  • CWE-116 Improper Encoding or Escaping of Output

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.