CVE-2026-45089 Dalfox: Unauthenticated Arbitrary File Create/Append via `output` Option in Dalfox Server Mode

What is CVE-2026-45089?

CVE-2026-45089 is a high-severity path traversal vulnerability in hahwul dalfox, published on 27 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

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.

Weakness: CWE-73, CWE-434, CWE-306

Which versions are affected by CVE-2026-45089?

4 open source packages ship an affected version, including github.com/hahwul/dalfox/v2 and github.com/hahwul/dalfox.

How do I fix CVE-2026-45089?

Upgrade github.com/hahwul/dalfox/v2 to 2.13.0 or later.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2026-45089 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45089 exists.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-8hf9-3q64-q2qf, GO-2026-5257.