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Fencer Vulns
high 8.8

CVE-2021-41178 json

File Traversal affecting SVG files on Nextcloud Server

published 2021-10-25 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-28280

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

Nextcloud is an open-source, self-hosted productivity platform. Prior to versions 20.0.13, 21.0.5, and 22.2.0, a file traversal vulnerability makes an attacker able to download arbitrary SVG images from the host system, including user provided files. This could also be leveraged into a XSS/phishing attack, an attacker could upload a malicious SVG file that mimics the Nextcloud login form and send a specially crafted link to victims. The XSS risk here is mitigated due to the fact that Nextcloud employs a strict Content-Security-Policy disallowing execution of arbitrary JavaScript. It is recommended that the Nextcloud Server be upgraded to 20.0.13, 21.0.5 or 22.2.0. There are no known workarounds aside from upgrading.

Patch / fix

  • nextcloud server 20.0.13, 21.0.5, 22.2.0
  • nextcloud Package Hub 15 SP3, Package Hub 15 SP2, Package Hub 15 SP1 +3 more 20.0.14-bp153.2.9.1

opensuse advisories openSUSE-SU-2021:1602-1

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-2021-41178 updated cvss 8.8

nextcloud: file traversal affecting SVG files

  • 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

1.78% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:P/I:N/A:N

Affected products

  • nextcloud security-advisories

Classification

Weakness
  • CWE-23 Relative Path Traversal
  • CWE-434 Unrestricted Upload of File with Dangerous Type
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

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.