CVE-2026-82778 Overview
CVE-2026-82778 is an information exposure vulnerability affecting the CONPROSYS PAC Series industrial controllers manufactured by Contec. The flaw allows a remote attacker to retrieve directory listings by accessing a specific URL on the device. The issue is classified under CWE-548: Exposure of Information Through Directory Listing.
Successful exploitation reveals filenames and directory structures stored on the device, which can aid reconnaissance for follow-on attacks against industrial control systems.
Critical Impact
Remote attackers can enumerate files and directory contents on affected CONPROSYS PAC Series devices, exposing information that supports reconnaissance and targeted attacks against operational technology environments.
Affected Products
- Contec CONPROSYS PAC Series industrial controllers
- Refer to the Contec Security Information Document for specific affected models and firmware versions
- See the JVN Security Vulnerability Report for coordinated disclosure details
Discovery Timeline
- 2026-09-14 - CVE-2026-82778 published to NVD
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-82778
Vulnerability Analysis
The vulnerability stems from improper configuration of the web interface exposed by CONPROSYS PAC Series devices. When a request is sent to a specific URL path, the device responds with a full directory listing rather than a default document or an access denied response.
An attacker requires network reachability to the device's web service. According to the advisory, the request does not require prior authentication to trigger directory disclosure. The exposed content is limited to file and directory names, but this metadata assists attackers in mapping the device filesystem and identifying configuration files, backups, or logs worth targeting in subsequent requests.
EPSS data indicates a low current probability of exploitation activity, but industrial controllers exposed to untrusted networks remain attractive reconnaissance targets.
Root Cause
The underlying cause is a missing access control policy on a directory served by the embedded HTTP server. The web server returns automatically generated index pages when no default document exists in the requested directory. This behavior [CWE-548] discloses information the application was not intended to expose to unauthenticated clients.
Attack Vector
Exploitation occurs over the network by issuing an HTTP GET request to the vulnerable URL path on the device's management interface. No credentials, user interaction, or specialized tooling are required. The attacker parses the returned HTML index to enumerate files and directories, then targets any sensitive resources uncovered during enumeration.
The vulnerability is described in prose only because no verified proof-of-concept code is published. Consult the JVN advisory and the Contec security bulletin for vendor-specific technical detail.
Detection Methods for CVE-2026-82778
Indicators of Compromise
- HTTP GET requests to CONPROSYS PAC Series devices returning HTML responses containing directory index markers such as Index of / or auto-generated file listings.
- Repeated unauthenticated requests from a single external source enumerating multiple URL paths on the device management interface.
- Web server access logs showing 200 OK responses to requests for directory paths without a default document.
Detection Strategies
- Inspect web server logs on CONPROSYS PAC Series devices for requests returning directory listing content types and unusually large HTML payloads for directory URLs.
- Deploy network intrusion detection signatures that flag HTTP responses containing directory index HTML patterns sourced from industrial control system asset IP ranges.
- Correlate reconnaissance-style HTTP scanning against OT assets with subsequent targeted requests for specific files revealed in the directory listing.
Monitoring Recommendations
- Forward device web server logs to a centralized log platform and alert on directory listing response patterns from ICS assets.
- Monitor perimeter firewalls for inbound HTTP or HTTPS traffic destined for CONPROSYS PAC Series management interfaces.
- Baseline normal administrative access to device web interfaces and alert on requests originating outside the expected administrator network segments.
How to Mitigate CVE-2026-82778
Immediate Actions Required
- Restrict network access to the CONPROSYS PAC Series web management interface using firewall rules that permit only authorized engineering workstations.
- Place affected devices behind a segmented OT network and block direct exposure to the internet or untrusted enterprise segments.
- Review web server access logs for prior evidence of directory enumeration and investigate any unexpected external sources.
Patch Information
Contec has published guidance in the Contec Security Information Document. Administrators should apply firmware updates or configuration changes as specified by the vendor. Additional coordinated disclosure information is available in the JVN advisory JVNVU96551518.
Workarounds
- Apply network-layer access control lists to permit HTTP or HTTPS access to affected devices only from trusted management hosts.
- Deploy a reverse proxy or web application firewall in front of the device that blocks requests to directory URLs lacking a default document.
- Disable or restrict the affected URL path at the network boundary until the vendor-provided remediation can be applied.
# Example: iptables rule restricting management access to a trusted subnet
iptables -A INPUT -p tcp --dport 80 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
