CVE-2026-45089CWE-306CWE-434CWE-73

Dalfox: Unauthenticated Arbitrary File Create/Append via `output` Option in Dalfox Server Mode

High · published May 27, 2026

CVSS v3.1
8.2
EPSS
0%
Percentile
33.1
In the wild
Unconfirmed
What it is

Dalfox is a powerful open-source XSS scanner and utility focused on automation. Prior to 2.13.0, when dalfox is run in REST API server mode, the output, output-all, and debug fields in model.Options are JSON-tagged and deserialized directly from the attacker's request body, then propagated unchanged through dalfox.Initialize into the scan engine's logging path. The logger opens the attacker-supplied path with os.O_APPEND|os.O_CREATE|os.O_WRONLY and writes scan log lines to it. Critically, this file write block lives outside the IsLibrary guard in DalLog, so it executes even in server/library mode where file output was never intended to operate. Because no API key is required in the default configuration, an unauthenticated network caller can create or append to any file writable by the dalfox process on the host filesystem. This vulnerability is fixed in 2.13.0.

The record
Technical detail
CVSS v3.1
8.2 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
CVSS v4.0
Not supplied
EPSS
0.00400 · 33.1th percentile
Weaknesses
CWE-306 · Missing Authentication for Critical Function; CWE-434 · Unrestricted Upload of File with Dangerous Type; CWE-73 · External Control of File Name or Path
Published
2026-05-27T17:33Z
EPSS history
Timeline
  • 27 MAY 17:33Z
    Dalfox: Unauthenticated Arbitrary File Create/Append via `output` Option in Dalfox Server Mode
    cvelistv5