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CVE-2023-28999

22
FAUCET Score

CVE-2023-28999 describes a critical vulnerability in Nextcloud Desktop, Android, and iOS clients (versions 3.0.0-3.8.0, 3.13.0-3.25.0, and 3.0.5-4.8.0 respectively) where a malicious server administrator can fully compromise end-to-end encrypted folders, decrypting files, recovering folder structures, and adding new content. This vulnerability carries a CVSS score of 6.4 (MEDIUM), indicating a high impact on confidentiality and integrity, with low attack complexity, requiring high privileges on the server. There are no known workarounds, but fixes are available in Nextcloud Desktop 3.8.0, Android 3.25.0, and iOS 4.8.0. Currently, there is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.0.0, < 3.8.0CPE matchmatch criteria
cpe:2.3:a:nextcloud:desktop:*:*:*:*:*:*:*:*
>= 3.0.5, < 4.8.0CPE matchmatch criteria
cpe:2.3:a:nextcloud:nextcloud:*:*:*:*:iphone_os:*:*:*
>= 3.13.0, < 3.25.0CPE matchmatch criteria
cpe:2.3:a:nextcloud:nextcloud:*:*:*:*:android:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.9MEDIUM

CVSS:3.1/AV:P/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L

Attack Vector
PHYSICAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
LOW
Exploitability Score
0.4
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.68%
Probability of exploitation in next 30 days
EPSS Percentile
48.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0068 is in the 86th percentile among its peer group of 4,937 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

ethz.ch / content/dam/ethz/special-interest/infk/inst-infsec/appliedcrypto/education/theses/report_DanieleCoppola.pdf
ExploitTechnical DescriptionThird Party Advisory
github.com / nextcloud/desktop/pull/5560
PatchVendor Advisory
github.com / nextcloud/security-advisories/security/advisories/GHSA-8875-wxww-3rr8
Vendor Advisory