Cyber Resilience

CVE-2026-34735

High

Published: 02 April 2026

Published
02 April 2026
Modified
16 April 2026
KEV Added
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Patch
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CVSS Score v4 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0031 22.1th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-34735 is a high-severity Unrestricted Upload of File with Dangerous Type (CWE-434) vulnerability. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 22.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability details

The Hytale Modding Wiki is a free service for Hytale mods to host their documentation & wikis. In version 1.2.0 and prior, the quickUpload() endpoint validates uploaded files by checking their MIME type (via PHP's finfo, which inspects file contents)…

more

but constructs the stored filename using the client-supplied file extension from getClientOriginalExtension(). These two checks are independent: an attacker can upload a file whose content passes the MIME allowlist while using a .php extension. The file is stored on the public disk and is directly accessible via URL, allowing server-side code execution. At time of publication no known patches exist.

CWE(s)
CWE-434

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1505.003 Web Shell Persistence
Adversaries may backdoor web servers with web shells to establish persistent access to systems.
attack.mitre.org →
Why these techniques?

Unrestricted file upload (CWE-434) on public wiki service directly enables web shell deployment via crafted PHP file after MIME bypass.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

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In
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

MP-7 Media Use
addresses: CWE-434

Requiring identifiable owners for portable devices reduces the attack surface for unrestricted uploads of dangerous file types via anonymous media.

SC-44 Detonation Chambers
addresses: CWE-434

Dangerous file uploads can be detonated in the chamber to determine malice before any production write or execution occurs.

SC-51 Hardware-based Protection
addresses: CWE-434

Prevents unrestricted writing of arbitrary or malicious firmware by keeping hardware write-protect enabled except under tightly controlled manual procedures.

SI-3 Malicious Code Protection
addresses: CWE-434

Scans files from external sources on download/open/execute, blocking unrestricted uploads of dangerous file types.

References