CVE-2025-66512: nextcloud nextcloud_server
CVSS: 6.1v3.1MediumAnalyzed
Published 05-12-2025Last modified 05-12-2025
Vulnerability summary
CVE-2025-66512 is a medium (CVSS 6.1) vulnerability in nextcloud nextcloud_server. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.2% of scored vulnerabilities.
CVSS score
6.1/10
010
Medium · v3.1 (NVD)EPSS score
0.28%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 05-12-2025PublishedVulnerability first disclosed.
- 05-12-2025Last modifiedVulnerability information updated.
Description
Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Server Enterprise prior to 31.0.12 and 32.0.3, a missing sanitization allowed malicious users to circumvent the content security policy when a malicious user manages to trick a user it viewing an uploaded SVG outside of the Nextcloud Servers web page.
CVSS metrics
2 scores · 2 sources · 1 versionMedium 6.1Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NSources2 sources · 5.4–6.1
- CVE.orgCNA5.4MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:LDiffers
EPSS trend
Probability
0.28%
Chance of exploitation in the next 30 days
Percentile
19%
Versus all other CVEs
30-day change
0.00 pp
From 0.28% on 19-09-2026
19-09-202619-10-2026
EPSS score0.28%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.
- CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Affected systems
Nextcloud2 products
- nextcloud_server≥ 31.0.0, < 31.0.12 | ≥ 32.0.0, < 32.0.3
- security-advisories≥ 32.0.0beta1, < 32.0.3 | < 31.0.12
1 vendor · 2 products
References
4 links- github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5X Refsource CONFIRMPatchVendor Advisory