CVE-2021-47955Public exploitNetwork attack vector

Stored cross-site scripting via malicious SVG upload

Published May 16, 2026 · Updated May 16, 2026

Stored cross-site scripting in CouchCMS 2.2.1 allows remote authenticated users to run JavaScript through a malicious SVG upload. The browse.php upload path accepts an SVG containing an embedded script element and stores it for browser rendering without neutralizing the script. An authenticated uploader must place the SVG and another user must access or preview it, exposing that user's browser session to script actions.

CVSS severity5.4
Medium
EPSS probability0.17%
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 CouchCMS 2.2.1 allows remote authenticated users to run JavaScript through a malicious SVG upload. The browse.php upload path accepts an SVG containing an embedded script element and stores it for browser rendering without neutralizing the script. An authenticated uploader must place the SVG and another user must access or preview it, exposing that user's browser session to script actions.

The record

CVE
CVE-2021-47955
Published
May 16, 2026
Updated
May 16, 2026
Vendor
CouchCMS
Product
CouchCMS
Classifications
CWE-79, T1204.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 16, 2026CVE publishedPublication date reported by the CVE source.
  2. May 16, 2026Record 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=2.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

CouchCMS · CouchCMSversion=2.2.1

Published CVSS scores

5.4VulnCheckCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.1VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA: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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.002User Execution: Malicious File

Public exploit references

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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