CVE-2026-72860 decolua · 9router

9router Server-Side Request Forgery via /api/provider-nodes/validate Because the IPv4-Mapped IPv6 Denylist Check Is Unre

Vulnerability at a glance

Severity, exploitation likelihood & attack requirements

CVSS v4.0 severity
6.3Medium
EPSS · exploitation likelihood
0.384% Probability within 30 daysPercentile 32.2
EPSS trend
Unchanged Since 2026-10-19
Known exploitation
Not in KEV CISA KEV catalog Absence does not establish safety
Attack vector
NetworkRemotely reachable
Attack complexity
LowFewer obstacles to exploitation
Privileges required
LowBasic privileges required
User interaction
NoneNo user action needed
Exploit availability & maturity
Not scored Availability not established No explicit exploit maturity assessment View exploit evidence
How to read the colors & trend
Higher exposureElevatedModerateLower exposureUnknown / unassessed

CVSS colors follow its reported severity. Attack-factor colors describe each requirement, not an overall risk rating. Gray also covers absence from KEV; absence does not establish safety.

EPSS display bands: below 1% blue, 1–10% amber, 10–50% orange, 50% and above red. These are presentation bands, not FIRST severity categories. The trend compares daily EPSS probabilities, not percentile ranks; “pp” means percentage points. The sparkline shows relative movement, with its vertical scale fitted to the observed scores.

Already protected by existing Atomicorp rules No new CVE-specific rule required.

Atomicorp ModSecurity protection

Protected by Atomicorp rules

Atomicorp ModSecurity rules block attacks exploiting this vulnerability. Keep your rules current.

By targeting underlying attack techniques and CWE weakness classes, existing rules can protect against newly disclosed vulnerabilities. Rule changes are regression-tested against attack and false-positive corpora.

6 rules identified Verified 2026-09-06 View rules & research details →

WAF protection does not change the CVSS or EPSS score. Keep your software patched and your Atomicorp rules current.

CISA SSVC assessment

CISA ADP · Assessed 2026-08-25 · SSVC 2.0.3

Exploitation
Proof-of-concept
Automatable
No
Technical Impact
Partial

Stakeholder-Specific Vulnerability Categorization records CISA’s assessment of exploitation, automation, and technical impact. “None reported” reflects the assessment date; it does not establish that no exploit exists. View SSVC source details.

On this page

CVE Details

Technical vulnerability details · CVSS assessments, exploit evidence & CPE data

CVSS assessments

CVSS v4.0 · disclosure@vulncheck.com

  • Base score: 6.3
  • Base severity: MEDIUM
  • Assessment type: Secondary
  • Source identifier: disclosure@vulncheck.com
  • Full vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
    • Attack vector: Network
    • Attack complexity: Low
    • Attack requirements: None
    • Privileges required: Low
    • User interaction: None
    • Vulnerable-system confidentiality: None
    • Vulnerable-system integrity: None
    • Vulnerable-system availability: None
    • Subsequent-system confidentiality: High
    • Subsequent-system integrity: Low
    • Subsequent-system availability: None
    • Safety: Not defined
  • Exploit maturity: Not scored

CVSS v3.1 · disclosure@vulncheck.com

  • Base score: 8.5
  • Base severity: HIGH
  • Exploitability subscore: 3.1
  • Impact subscore: 4.7
  • Assessment type: Secondary
  • Source identifier: disclosure@vulncheck.com
  • Full vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
    • Attack vector: Network
    • Attack complexity: Low
    • Privileges required: Low
    • User interaction: None
    • Scope: Changed
    • Confidentiality impact: High
    • Integrity impact: Low
    • Availability impact: None
  • Exploit maturity: Not scored

Exploitability and impact subscores describe the vulnerability’s technical characteristics. Exploit maturity describes the reported state of exploitation; these are separate measures.

Assessment source: NVD record · CVE record

CISA SSVC assessments

These are CISA’s published decision points at the assessment time. They are not a complete organization-specific prioritization decision.

  • Provider: CISA ADP
  • Provider identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  • SSVC version: 2.0.3
  • Role: CISA Coordinator
  • Assessment timestamp: 2026-08-25T15:26:55.977320Z
  • Exploitation: poc
  • Automatable: no
  • Technical Impact: partial
  • Source: CISA ADP in the CVE record

Vulnerable CPE configurations

No vulnerable CPE configurations are supplied in the current NVD record. See the affected-product information and vendor guidance on this page.

Vulnerability Description

The POST /api/provider-nodes/validate route in 9router takes a caller-supplied baseUrl and issues server-side HTTP requests to it, guarding the destination with assertPublicUrl from src/shared/utils/ssrfGuard.js. That guard compares hostname strings only: it resolves no DNS, does not revalidate after a redirect, and its IPv4-mapped IPv6 branch is unreachable. The branch matches ^::ffff:(\d+.\d+.\d+.\d+)$, but the WHATWG URL parser canonicalizes such literals to hextets before the guard runs, so new URL(“http://[::ffff:127.0.0.1]/”).hostname yields [::ffff:7f00:1] and the pattern is tested against a string it is never handed. Every IPv4-mapped address therefore passes, and http://[::ffff:7f00:1] and http://[::ffff:a9fe:a9fe] reach loopback and link-local metadata addresses; a hostname whose A record points at an internal address passes as well because no resolution occurs. In the custom-embedding branch the upstream response body is truncated to 200 bytes and returned to the caller whenever the upstream status is neither 2xx nor 401 nor 403, which discloses the beginning of internal responses, and the other validation types remain usable for blind internal port scanning through status and timing differences. The caller-supplied apiKey is forwarded to the internal destination as an Authorization Bearer header. A dashboard session is required by default, and none is required when requireLogin is disabled.

  1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (337109 , 337110 , 344360 , 390719 , 398021 , 398022 ) have not been locally disabled. Atomicorp commercial rules are enabled by default. If you use Atomic WAF, review the applicable policy and rule settings.

  2. Apply the vendor’s remediation. WAF protection is defense in depth and does not replace upgrading or following the affected vendor’s guidance.

    • Affected versions: decolua 9router versions through 0.5.55.
    • No specific CNA/vendor solution or workaround is included in the current CVE Record . Review the vendor’s security advisories and supported-release guidance before making changes.

  3. Validate after changes. Confirm rule updates are current, review WAF events for the affected application, and test application behavior after vendor upgrades, mitigations, or local policy changes.

Research Notes

Atomicorp WAF protections are designed around attack techniques and exploit behaviors, allowing existing protections to apply across multiple vulnerabilities without requiring a unique rule for every CVE.

Public Vulnerability References

Test or Research Source

  • Source: Atomicorp AI Research Framework
  • Tags: cve, derived, ssrf, waf-probe

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

  • Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
  • Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
  • Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
  • Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
  • Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ .