Vulnerability · Published May 27, 2026 · Assigned by GitHub_M
CVE-2026-45089Dalfox: Unauthenticated Arbitrary File Create/Append via `output` Option in Dalfox Server Mode
High 8.2
In plain English
A high-severity missing authentication in dalfox from hahwul. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/hahwul/dalfox | no fix listed | GO-2026-5257 |
| Go | github.com/hahwul/dalfox/v2 | 2.13.0 | GHSA-8hf9-3q64-q2qf |
| Go | github.com/hahwul/dalfox/v2 | 2.13.0 | GO-2026-5257 |
Affected products (as reported)
Weakness: CWE-73, CWE-306, CWE-434 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
References
- https://github.com/hahwul/dalfox/security/advisories/GHSA-8hf9-3q64-q2qf x_refsource_CONFIRM
- https://github.com/hahwul/dalfox/releases/tag/v2.13.0 x_refsource_MISC