CVE-2025-15104
CVE-2025-15104 is a medium-severity vulnerability in Validator with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-918.
Key facts
- Severity: Medium (CVSS 3.x base score 5.3)
- CVSS v4: 6.9
- EPSS exploit prediction: 0% (34th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-2919
- Weakness: CWE-918
- Affected product: Validator
- Published:
- Last modified:
Description
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).
Frequently asked questions
- What is CVE-2025-15104?
- 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).
- How severe is CVE-2025-15104?
- CVE-2025-15104 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
- Is CVE-2025-15104 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-15104?
- CVE-2025-15104 affects Validator. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2025-15104?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2025-15104 have an EU (EUVD) identifier?
- Yes. CVE-2025-15104 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2919.
- When was CVE-2025-15104 published?
- CVE-2025-15104 was published on 2026-01-16 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:validator:validator:*:*:*:*:*:*:*:*
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