CVE-2021-41178

File Traversal affecting SVG files on Nextcloud Server

MEDIUM
6.5
CVSS Score
Published: October 25, 2021 at 09:55 PM UTC
Updated: June 17, 2026 at 04:08 AM UTC
1 product affected across 1 vendorNextcloud/server

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Severity
MEDIUM6.5
Exploit prediction
EPSS 2%

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

20.0.3 ≤ v < 20.0.1321.0.1 ≤ v < 21.0.522.1.1 ≤ v < 22.2.0
Affected range stops below 20.0.13, so it looks safe — our inference, not a vendor statement
Affected range stops below 21.0.5, so it looks safe — our inference, not a vendor statement
Affected range stops below 22.2.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_MISCPatchThird Party Advisory
https://github.com/nextcloud/server/pull/28726
x_refsource_MISCPermissions Required
https://hackerone.com/reports/1302155
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
https://security.gentoo.org/glsa/202208-17

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-23CWE-434CWE-22

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