CVE-2020-8294Network attack vector

Stored XSS via missing link validation

Published Feb 3, 2021 · Updated Aug 4, 2024

Stored cross-site scripting in Nextcloud Server before 20.0.2, 19.0.5, or 18.0.11 allows remote authenticated users to execute script in Internet Explorer. Missing validation accepts a javascript: URL when a user saves a markdown link, leaving the payload stored for later rendering. Exploitation requires an authenticated user to save crafted markdown and a victim to open it in Internet Explorer; the documented impact is script execution in that browser context.

CVSS severity5.4
Medium
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Nextcloud Server before 20.0.2, 19.0.5, or 18.0.11 allows remote authenticated users to execute script in Internet Explorer. Missing validation accepts a javascript: URL when a user saves a markdown link, leaving the payload stored for later rendering. Exploitation requires an authenticated user to save crafted markdown and a victim to open it in Internet Explorer; the documented impact is script execution in that browser context.

The record

CVE
CVE-2020-8294
Published
Feb 3, 2021
Updated
Aug 4, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Server
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 3, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=Fixed in 20.0.2, 19.0.5, 18.0.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Serverversion=Fixed in 20.0.2, 19.0.5, 18.0.11

Published CVSS scores

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NVDAV:N/AC:M/Au:S/C:N/I:P/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-79Cross-site Scripting (XSS) - Stored
T1189Drive-by Compromise

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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