CVE-2023-33977Network attack vector

Stored XSS via unchecked SVG onload attributes

Published Jun 6, 2023 · Updated Jan 7, 2025

Stored XSS in attachment validation in Kiwi TCMS 12.3 and earlier allows attackers to execute JavaScript through uploaded SVG files. The attachment validator rejected script tags but failed to reject executable SVG onload attributes, allowing a crafted image to retain browser-executed code. Exploitation requires submitting the crafted attachment and another user viewing it; reverse proxies that strip protective headers increase exposure.

CVSS severity8.1
High
EPSS probability0.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in attachment validation in Kiwi TCMS 12.3 and earlier allows attackers to execute JavaScript through uploaded SVG files. The attachment validator rejected script tags but failed to reject executable SVG onload attributes, allowing a crafted image to retain browser-executed code. Exploitation requires submitting the crafted attachment and another user viewing it; reverse proxies that strip protective headers increase exposure.

The record

CVE
CVE-2023-33977
Published
Jun 6, 2023
Updated
Jan 7, 2025
Vendor
Kiwi TCMS
Product
Kiwi TCMS
Classifications
CWE-79, CWE-434, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 7, 2025Record 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=< 12.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kiwi TCMS · Kiwi TCMSversion=< 12.4

Published CVSS scores

8.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
5.4NIST 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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-434Unrestricted Upload of File with Dangerous Type
T1059.007Command and Scripting Interpreter: JavaScript/JScript

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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