Atomicorp WAF Research Note: CVE-2026-18147

Freeipa: ipa: freeipa/idm: cross-site scripting vulnerability allows arbitrary code execution via crafted url

CVE Details

• Already protected by existing Atomicorp WAF rules
• Protection status: Understanding Atomicorp WAF Protection Status
• CVE: CVE-2026-18147
• Name: Freeipa: ipa: freeipa/idm: cross-site scripting vulnerability allows arbitrary code execution via crafted url
• Severity: High
• CVSS: 8.1 (v3.1) (High)
• CVSS version: 3.1
• CVSS source: redhat CNA
• CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
  • Attack vector: Network
  • Attack complexity: Low
  • Privileges required: None
  • User interaction: Required
  • Scope: Unchanged
  • Confidentiality impact: High
  • Integrity impact: High
  • Availability impact: None
• CWE: CWE-79 — Improper Neutralization of Input During Web Page Generation (‘Cross-site Scripting’)
• Related CAPEC attack patterns (via MITRE CWE relationships): CAPEC-209 (opens in a new tab) , CAPEC-588 (opens in a new tab) , CAPEC-591 (opens in a new tab) , CAPEC-592 (opens in a new tab) , CAPEC-63 (opens in a new tab) , CAPEC-85 (opens in a new tab)
• Vendor: Red Hat
• Vulnerable products: Red Hat Enterprise Linux 10 , Red Hat Enterprise Linux 6 , Red Hat Enterprise Linux 7 , Red Hat Enterprise Linux 8 , Red Hat Enterprise Linux 9
• CVE published: 2026-09-09
• CVE last modified: 2026-09-10
• EPSS: 0.0029; 21.7th percentile (FIRST (opens in a new tab) )
• Latest Update: 2026-09-10
• Selected Rule IDs observed: 333140 , 333141 , 340087 , 340095 , 340099 , 340147 , 341099 , 341266 , 342259
• Matching rules: 9; rules with blocking actions: 9
• Would-block Rule IDs: 333140 , 333141 , 340087 , 340095 , 340099 , 340147 , 341099 , 341266 , 342259
• Request surfaces inspected: JSON request data, Request URI, Request argument names, Request arguments, Request cookies, Request headers, SOAP request data, XML request data

Vulnerability Description

A flaw was found in FreeIPA. An unauthenticated remote attacker could exploit a DOM Cross-Site Scripting (XSS) vulnerability in the FreeIPA/IdM Web UI password reset page. By enticing a victim to click a specially crafted link and complete a password reset, the attacker could inject and execute arbitrary JavaScript code. This allows the attacker to perform actions within the victim’s authenticated session, potentially leading to full administrative control if an IdM administrator is targeted.

Recommended Actions

1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (333140 , 333141 , 340087 , 340095 , 340099 , 340147 , 341099 , 341266 , 342259 ) 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.

   • CNA guidance source: redhat (opens in a new tab)
   • Vendor workaround: Restrict network access to the FreeIPA/IdM Web UI to trusted networks only. This can be achieved by configuring firewall rules to limit access to the IdM server’s web interface (typically port 443 for HTTPS) from specific IP addresses or subnets. For example, using firewalld on RHEL, you can add a rich rule to allow access only from trusted sources. Ensure that any firewall changes are persistent across reboots and that the firewall service is reloaded or restarted for changes to take effect, which may temporarily disrupt access to the IdM Web UI.

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

• NVD (opens in a new tab)
• CVE Record (opens in a new tab)
• CVE authority reference: https://access.redhat.com/security/cve/CVE-2026-18147 (opens in a new tab)
• CVE authority reference: https://bugzilla.redhat.com/show_bug.cgi?id=2508181 (opens in a new tab)

Test or Research Source

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

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/ (opens in a new tab) .