Server-side Request Forgery (SSRF) Affecting html5validator package, versions [0,]
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-HTML5VALIDATOR-15010792
- published2 Feb 2026
- disclosed16 Jan 2026
- creditOscar Uribe
Introduced: 16 Jan 2026
NewCVE-2025-15104 (opens in a new tab)How to fix?
There is no fixed version for html5validator.
Overview
html5validator is a Validate HTML5 files.
Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) due to the improper implementation of localhost bypass protection. An attacker can cause the server to initiate arbitrary HTTP or HTTPS requests to internal network resources by using DNS rebinding resulting in to loopback addresses, including those on localhost, by bypassing hostname-based protections using DNS rebinding techniques or domains that resolve to loopback addresses.