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01 Record

CVE-2025-66550

Nextcloud Calendar attachments of local files are offered to downloaded

MediumPUBLISHEDCNA: GitHub_M
CNA base score5.7 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
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02 Description

Nextcloud Calendar attachments of local files are offered to downloaded

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.34% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 27.3% of scored records. A rank, not a probability.
NVD base score
5.7 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
NVD analysis status
Analyzed. NVD last modified this record on 2026-10-18.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2025-12-05 16:56Z10 MO AGO
Last updated
2025-12-05 18:41Z10 MO AGO
Reserved
2025-12-04
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
Medium (CVSS 5.7)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
Weaknesses
  • CWE-241Improper Handling of Unexpected Data TypeBase
Data version
5.2
Document digest
b61c2f226a915523ff09d5d3a2929b52e88b0811cc66baff2c883548db99aa0c

05 Affected products

VendorProductVersionsPlatforms
nextcloudsecurity-advisories>= 5.0.0-rc.1, < 5.2.4, < 4.7.17—

06 References