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Fencer Vulns
medium 6.7

CVE-2023-28998 json

Nextcloud Desktop client misbehaves with E2EE when the server returns empty list of metadata keys

published 2023-04-04 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-32616

cvss
6.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server. Starting with version 3.0.0 and prior to version 3.6.5, a malicious server administrator can gain full access to an end-to-end encrypted folder. They can decrypt files, recover the folder structure, and add new files.​ Users should upgrade the Nextcloud Desktop client to 3.6.5 to receive a patch. No known workarounds are available.

Patch / fix

  • nextcloud desktop 3.6.5
  • nextcloud-desktop Debian 14, Debian 13, Debian 12 3.7.0-1

debian advisories DEBIAN-CVE-2023-28998

  • nextcloud-client Alpine 3.24, Alpine 3.23, Alpine 3.22 +4 more 3.6.6-r0

alpine advisories ALPINE-CVE-2023-28998

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-28998 updated

nextcloud: Multiple vulnerabilities

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
20 mo ago

Exploit prediction

0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • ethz.ch https://ethz.ch/content/dam/ethz/special-interest/infk/inst-infsec/appliedcrypto/education/theses/report_DanieleCoppola.pdf referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.7 CVSS:3.1/AV:P/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N

Affected products

  • nextcloud security-advisories

Classification

Weakness
  • CWE-325 Missing Cryptographic Step

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.