CVE-2026-3749Public exploitNetwork attack vector

Stored XSS via unsanitized SVG upload

Published Mar 8, 2026 · Updated Mar 8, 2026

Stored cross-site scripting in Bytedesk 1.3.0 through 1.3.9 allows remote authenticated users to execute JavaScript via uploaded SVG files. The handleFileUpload path accepts SVG content, and UploadWatermarkService writes the original file to disk when image decoding or watermarking fails instead of rejecting it. The attacker needs an authenticated upload session, and script execution occurs when a visitor opens the returned public file URL.

CVSS severity8.8
High
EPSS probability0.42%
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 Bytedesk 1.3.0 through 1.3.9 allows remote authenticated users to execute JavaScript via uploaded SVG files. The handleFileUpload path accepts SVG content, and UploadWatermarkService writes the original file to disk when image decoding or watermarking fails instead of rejecting it. The attacker needs an authenticated upload session, and script execution occurs when a visitor opens the returned public file URL.

The record

CVE
CVE-2026-3749
Published
Mar 8, 2026
Updated
Mar 8, 2026
Vendor
Bytedesk
Product
Bytedesk
Classifications
CWE-434, CWE-284, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 8, 2026Record 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=1.3.0
  2. Affected versionversion=1.3.1
  3. Affected versionversion=1.3.2
  4. Affected versionversion=1.3.3
  5. Affected versionversion=1.3.4
  6. Affected versionversion=1.3.5
  7. Affected versionversion=1.3.6
  8. Affected versionversion=1.3.7
  9. Affected versionversion=1.3.8
  10. Affected versionversion=1.3.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Bytedesk · Bytedeskversion=1.3.0; version=1.3.1; version=1.3.2; version=1.3.3; version=1.3.4; version=1.3.5; version=1.3.6; version=1.3.7; version=1.3.8; version=1.3.9

Published CVSS scores

2.1VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
8.8NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5VulDBAV:N/AC:L/Au:S/C:P/I:P/A:P
6.3VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

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-434Unrestricted Upload of File with Dangerous Type
CWE-284Improper Access Control
T1190Exploit Public-Facing Application

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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