CVE-2021-29460Public exploitNetwork attack vector

Privilege escalation via unvalidated SVG or XML uploads

Published Apr 27, 2021 · Updated Aug 3, 2024

Stored XSS in Content Folder Kirby before 3.5.4 allows remote authenticated users to execute scripts through uploaded SVG or XML files. Kirby's upload path stored and served active SVG or XML content without validating embedded script elements. An editor needs Panel write access and must persuade a victim to open the file; code then runs in the victim's session and can invoke the API with that user's permissions.

CVSS severity7.6
High
EPSS probability3.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in Content Folder Kirby before 3.5.4 allows remote authenticated users to execute scripts through uploaded SVG or XML files. Kirby's upload path stored and served active SVG or XML content without validating embedded script elements. An editor needs Panel write access and must persuade a victim to open the file; code then runs in the victim's session and can invoke the API with that user's permissions.

The record

CVE
CVE-2021-29460
Published
Apr 27, 2021
Updated
Aug 3, 2024
Vendor
Content Folder
Product
Kirby
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 27, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 3.5.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Content Folder · Kirbyversion=< 3.5.4

Published CVSS scores

7.6GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001User Execution: Malicious Link

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo