Headline
GHSA-fccg-7w3p-w66f: Nu Html Checker (vnu) contains a Server-Side Request Forgery (SSRF) vulnerability
Nu Html Checker (validator.nu) contains a restriction bypass that allows remote attackers to make the server perform arbitrary HTTP/HTTPS requests to internal resources, including localhost services. While the validator implements hostname-based protections to block direct access to localhost and 127.0.0.1, these controls can be bypassed using DNS rebinding techniques or domains that resolve to loopback addresses.This issue affects The Nu Html Checker (vnu): latest (commit 23f090a11bab8d0d4e698f1ffc197a4fe226a9cd).
- GitHub Advisory Database
- GitHub Reviewed
- CVE-2025-15104
Nu Html Checker (vnu) contains a Server-Side Request Forgery (SSRF) vulnerability
Moderate severity GitHub Reviewed Published Jan 16, 2026 to the GitHub Advisory Database • Updated Jan 16, 2026
Package
maven nu.validator:validator (Maven)
Affected versions
<= 26.1.11
Nu Html Checker (validator.nu) contains a restriction bypass that allows remote attackers to make the server perform arbitrary HTTP/HTTPS requests to internal resources, including localhost services. While the validator implements hostname-based protections to block direct access to localhost and 127.0.0.1, these controls can be bypassed using DNS rebinding techniques or domains that resolve to loopback addresses.This issue affects The Nu Html Checker (vnu): latest (commit 23f090a11bab8d0d4e698f1ffc197a4fe226a9cd).
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-15104
- https://fluidattacks.com/advisories/europe
- https://github.com/validator/validator
Published to the GitHub Advisory Database
Jan 16, 2026
Last updated
Jan 16, 2026