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Atomicorp WAF Research Note: CVE-2026-81931

Unrestricted upload of file with dangerous type in Prospero Flow CRM product photo allows stored cross-site scripting

CVE Details

Status: Attack Blocked by Atomicorp
  • Already protected by existing Atomicorp WAF rules
  • Protection status: Understanding Atomicorp WAF Protection Status
  • CVE: CVE-2026-81931
  • Name: Unrestricted upload of file with dangerous type in Prospero Flow CRM product photo allows stored cross-site scripting
  • Severity: Medium
  • CVSS: 4.8 (v4.0) (Medium)
  • CVSS version: 4.0
  • CVSS source: Secur0 CNA
  • CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:L/VA:N/SC:N/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: Active
    • Vulnerable-system confidentiality: None
    • Vulnerable-system integrity: Low
    • Vulnerable-system availability: None
    • Subsequent-system confidentiality: None
    • Subsequent-system integrity: Low
    • Subsequent-system availability: None
    • Scope: X
  • CWE: CWE-434 — Unrestricted Upload of File with Dangerous Type
  • Related CAPEC attack patterns (via MITRE CWE relationships): CAPEC-1
  • Vendor: Roskus
  • Vulnerable product: Prospero Flow CRM
  • CVE published: 2026-08-27
  • CVE last modified: 2026-09-01
  • EPSS: 0.0029; 21.0th percentile (FIRST )
  • Latest Update: 2026-09-06
  • Selected Rule IDs observed: 351000
  • Matching rules: 1; rules with blocking actions: 1
  • Would-block Rule IDs: 351000

Vulnerability Description

Unrestricted Upload of File with Dangerous Type in the product photo upload in Roskus Prospero Flow CRM before 5.16.0 allows an authenticated user holding the create product permission (routine Seller role) to execute arbitrary JavaScript in the application origin. The photo validation rule classifies the file only by its content (magic bytes) and rejects only a fixed list of PHP extensions, while ProductSaveController::save() names the stored file using the client-supplied extension and copies it into the public web root. A file that begins with an image header and carries an HTML extension passes validation, is stored under public/asset/upload/product/, and is served with a text/html content type, turning the upload into first-party stored script execution.

  1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (351000 ) 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: Roskus Prospero Flow CRM versions earlier than 5.16.0.
    • Recommended upgrade: Upgrade Roskus Prospero Flow CRM to 5.16.0 or later.
    • CNA guidance source: Secur0
    • Vendor recommendation: Upgrade to 5.16.0 or later from the main branch; no tagged release carries the fix. Review and remove any existing files with a non-image extension under public/asset/upload/product/.

  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, upload, 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/ .