Missing sanitization of a server response in Nextcloud Desktop Client 2.6.4 for Linux allowed a malicious Nextcloud Server to store files o…

published 2020-08-21 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-29099

cvss: 6.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 25.8%; EPSS 25.8% chance of exploitation in 30 days, percentile 97%
public exploits: 0; none known

Missing sanitization of a server response in Nextcloud Desktop Client 2.6.4 for Linux allowed a malicious Nextcloud Server to store files outside of the dedicated sync directory.

Patch / fix

fixed in 1 distros 1

nextcloud desktop 2.6.5

nextcloud-desktop Debian 14, Debian 13, Debian 12 3.0.1-1

debian advisories DEBIAN-CVE-2020-8227

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-2020-8227 updated 2025-11-21 cvss 5.1

nextcloud: missing sanitization of a server response leads to store files outside of dedicated sync directory

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

Exploit prediction

25.77% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

hackerone.com https://hackerone.com/reports/590319 referenced PoC, tagged "exploit" by a source, unverified
nextcloud.com https://nextcloud.com/security/advisory/?id=NC-SA-2020-032 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	6.8	CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H
NVD	2.0	7.1	AV:N/AC:H/Au:S/C:C/I:C/A:C

Affected products

n/a Desktop Client

Classification

Weakness

CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

hackerone.com /reports/590319
exploit, third-party-advisory
nextcloud.com /security/advisory/?id=NC-SA-2020-032
broken-link, exploit, vendor-advisory
security.gentoo.org /glsa/202009-09
vendor-advisory, third-party-advisory

Sources

CVE List CVE-2020-8227
NVD CVE-2020-8227

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.

Summary