CVE-2021-41178Network attack vector

Authenticated SVG disclosure via unchecked path traversal

Published Oct 25, 2021 · Updated Aug 4, 2024

Relative path traversal in Nextcloud Server before 20.0.13, 21.0.5, and 22.2.0 allows remote authenticated users to download SVG files. The SVG color API combines attacker-controlled app and image path segments with server-side asset paths without rejecting relative traversal sequences. A valid account is required; strict Content Security Policy blocks arbitrary JavaScript, but crafted SVGs can support credential phishing.

CVSS severity8.8
High
EPSS probability1.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Relative path traversal in Nextcloud Server before 20.0.13, 21.0.5, and 22.2.0 allows remote authenticated users to download SVG files. The SVG color API combines attacker-controlled app and image path segments with server-side asset paths without rejecting relative traversal sequences. A valid account is required; strict Content Security Policy blocks arbitrary JavaScript, but crafted SVGs can support credential phishing.

The record

CVE
CVE-2021-41178
Published
Oct 25, 2021
Updated
Aug 4, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-434, CWE-23, CWE-22, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=20.0.13
  2. Affected versionversion=>= 21.0.0, < 21.0.5
  3. Affected versionversion=< 22.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Security Advisoriesversion=20.0.13; version=>= 21.0.0, < 21.0.5; version=< 22.2.0

Published CVSS scores

8.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
CWE-23Relative Path Traversal
CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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