CVE-2020-8280Known exploitationNetwork attack vector

Stored XSS via SVG type confusion

Published Jan 6, 2021 · Updated Aug 4, 2024

Cross-site scripting in Nextcloud Contacts 3.4.0 allows remote authenticated users to upload SVG files that the app accepts as PNG images. The upload validation checks the filename or declared image type without verifying the file's actual content, so browser-rendered SVG markup executes in the Contacts context. Exploitation requires a valid user account able to upload contact images and a victim who views the resulting contact; the demonstrated impact is script execution with confidentiality and integrity effects in that web session, not server-side code execution.

CVSS severity5.4
Medium
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Nextcloud Contacts 3.4.0 allows remote authenticated users to upload SVG files that the app accepts as PNG images. The upload validation checks the filename or declared image type without verifying the file's actual content, so browser-rendered SVG markup executes in the Contacts context. Exploitation requires a valid user account able to upload contact images and a victim who views the resulting contact; the demonstrated impact is script execution with confidentiality and integrity effects in that web session, not server-side code execution.

The record

CVE
CVE-2020-8280
Published
Jan 6, 2021
Updated
Aug 4, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Contacts
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 6, 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 3.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Contactsversion=Fixed in 3.4.1

Published CVSS scores

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
4.0NVDAV: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 exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

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Reported exploitation

Technologies

Your stack

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Your stack

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