CVE-2026-3748: Bytedesk SVG File UploadRestController.java uploadFile unrestricted upload
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
A security flaw has been discovered in Bytedesk up to 1.3.9. This affects the function uploadFile of the file source-code/src/main/java/com/bytedesk/core/upload/UploadRestController.java of the component SVG File Handler. Performing a manipulation results in unrestricted upload. Remote exploitation of the attack is possible. The exploit has been released to the public and may be used for attacks. Upgrading to version 1.4.5.1 is able to mitigate this issue. The patch is named 975e39e4dd527596987559f56c5f9f973f64eff7. Upgrading the affected component is recommended.
Description quoted from the CVE record (assigned by VulDB, published 2026-03-08).
Weakness: Unrestricted Upload; Improper Access Controls
How it can be exploited
Exploitable over the network with low attack complexity with no special attack requirements needing low privileges and no user interaction. Impact: confidentiality low, integrity low, availability low. CVSS: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
CISA assessment (SSVC): CISA assesses that a public proof of concept exists. Automatable: no. Technical impact: partial.
Public exploit evidence (Exploit Observer)
Also known as: EUVD-2026-10251, GHSA-x2c8-qgvg-23wq
VEDAS cluster: VEDAS:CURSEDBULLET
Exploit Observer links 3 pieces of public exploit code or detection modules that name this CVE or one of its aliases.
Exploit code and modules (3)
Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.
- Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-3748.rules
- Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-3748.rules
- Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-3748.rules
Vulnerability databases and vendor advisories (3)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-10251
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-x2c8-qgvg-23wq
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-3748
2 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.005
low predicted chance of attack - VEDAS
- 0.977
strong exploit evidence - On CISA KEV
- Not listed
- Detection rule
- Suricata
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Bytedesk | version 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 and 2 more ranges | 1.4.5.1 is not affected |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: bytedesk bytedesk.
How to fix it
Vendor guidance:
- https://github.com/Bytedesk/bytedesk/commit/975e39e4dd527596987559f56c5f9f973f64eff7 (patch)
- https://github.com/Bytedesk/bytedesk/releases/tag/v1.4.5.1 (patch)
How to detect it
Suricata rules (network detection)
1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-3748 Bytedesk - Unrestricted SVG File Upload. Add them to your Suricata rule set and reload.
Show the rules
# CVE-2026-3748 - Bytedesk <= 1.3.9 unrestricted file upload. UploadRestController.uploadFile
# accepts SVG files without validating type/content, so an attacker POSTs a crafted SVG to
# POST /api/v1/upload/file (multipart field 'file'). Matches the multipart upload of an SVG
# declared as image/svg+xml with embedded script (file upload -> network detection only).
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-3748 Bytedesk - Unrestricted SVG File Upload"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/api/v1/upload/file"; nocase; fast_pattern; http.request_body; content:"image/svg+xml"; nocase; content:"<script"; nocase; classtype:web-application-attack; reference:cve,CVE-2026-3748; reference:url,https://www.exploit.observer/?keyword=CVE-2026-3748&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=bytedesk&match=exact; sid:1101404; rev:1;)
References
Vendor advisories and patches
- https://github.com/Bytedesk/bytedesk/commit/975e39e4dd527596987559f56c5f9f973f64eff7 (patch)
- https://github.com/Bytedesk/bytedesk/releases/tag/v1.4.5.1 (patch)
Exploits and technical analysis
- VDB-349726 | Bytedesk SVG File UploadRestController.java uploadFile unrestricted upload (vdb-entry, technical-description)
- Submit #768028 | Bytedesk <=1.3.9 Unrestricted Upload of File with Dangerous Type (CWE-434) (third-party-advisory)
- https://github.com/Bytedesk/bytedesk/issues/18 (issue-tracking)
- https://github.com/Bytedesk/bytedesk/issues/18#issuecomment-3976672973 (issue-tracking)
- https://github.com/Bytedesk/bytedesk/issues/18#issue-3993448721 (exploit, issue-tracking)
Other references
- VDB-349726 | CTI Indicators (IOB, IOC, TTP, IOA) (signature, permissions-required)
- https://github.com/Bytedesk/bytedesk/ (product)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.