CVE-2026-9085: Pardus Parental Control Auth Bypass Flaw

CVE-2026-9085 Overview

CVE-2026-9085 is an improper access control vulnerability in TUBITAK BILGEM Software Technologies Research Institute's Pardus-Parental-Control software. The flaw combines Incorrect Permission Assignment for Critical Resource with Improper Access Control [CWE-284], allowing a local authenticated attacker to conduct DNS spoofing attacks. The vulnerability affects Pardus-Parental-Control versions <=0.5.1 prior to 0.7.0. A successful attack redirects DNS resolution, breaking the integrity of parental control policies and enabling redirection of traffic to attacker-controlled endpoints.

Critical Impact
Local attackers with low privileges can manipulate DNS resolution to bypass content filtering, redirect users to malicious hosts, and compromise confidentiality, integrity, and availability across the affected system boundary.

Affected Products

TUBITAK BILGEM Pardus-Parental-Control versions <=0.5.1
All releases prior to Pardus-Parental-Control 0.7.0
Pardus Linux endpoints running the vulnerable parental control component

Discovery Timeline

2026-07-05 - CVE-2026-9085 published to the National Vulnerability Database
2026-07-06 - Last updated in the NVD database

Technical Details for CVE-2026-9085

Vulnerability Analysis

The vulnerability originates from incorrect permission assignments on critical resources used by Pardus-Parental-Control. The affected component fails to enforce proper access control on files or configuration objects that influence DNS resolution behavior. A local user with low privileges can modify these resources without holding administrative rights. Because the compromise crosses a trust boundary, the scope is changed, extending the impact beyond the vulnerable component itself.

Once the attacker alters the DNS-related configuration, the system resolves hostnames using attacker-supplied data. This DNS spoofing primitive undermines the parental control policy engine, which relies on trusted name resolution to enforce category-based blocking. Attackers can redirect blocked domains to permitted hosts or reroute legitimate services to malicious infrastructure.

Root Cause

The root cause is Incorrect Permission Assignment for Critical Resource combined with Improper Access Control [CWE-284]. Configuration files, sockets, or IPC endpoints governing DNS behavior are exposed to unprivileged users. The application does not validate whether the calling identity holds the authority required to modify security-relevant DNS state.

Attack Vector

The attack requires local access with low privileges and no user interaction. An authenticated attacker on a Pardus workstation manipulates the writable resource to inject arbitrary DNS mappings or overrides. Subsequent name lookups performed by the system, browsers, or the parental control agent itself return attacker-controlled addresses.

No verified public exploitation code exists for CVE-2026-9085. Detailed technical information is available in the Siber Güvenlik Notification TR-26-0500.

Detection Methods for CVE-2026-9085

Indicators of Compromise

Unexpected modifications to Pardus-Parental-Control configuration files or DNS-related override files by non-root users
Sudden changes to /etc/resolv.conf, /etc/hosts, or parental control policy databases on Pardus endpoints
DNS responses for filtered domains resolving to unexpected IP addresses
Local processes writing to parental control resources outside of the vendor update workflow

Detection Strategies

Monitor file integrity for Pardus-Parental-Control installation directories and any files referenced by the DNS resolution path
Alert on chmod, chown, or write operations against parental control resources performed by non-privileged accounts
Correlate DNS query telemetry with expected parental control policy to identify silent policy bypass

Monitoring Recommendations

Enable audit rules (auditd) on all Pardus-Parental-Control configuration paths and DNS resolver files
Capture endpoint DNS traffic and compare resolutions against the sanctioned upstream resolver
Track the installed Pardus-Parental-Control package version across the fleet and flag any host below 0.7.0

How to Mitigate CVE-2026-9085

Immediate Actions Required

Upgrade Pardus-Parental-Control to version 0.7.0 or later on every affected endpoint
Audit permissions on all Pardus-Parental-Control configuration files and restrict write access to root
Review recent modifications to DNS resolver configuration and parental control policy files for signs of tampering
Restrict local shell access on Pardus workstations to trusted administrators until patching completes

Patch Information

TUBITAK BILGEM addresses the vulnerability in Pardus-Parental-Control version 0.7.0. Administrators should install the fixed release through the Pardus package management system. Refer to the Siber Güvenlik Notification TR-26-0500 for vendor guidance.

Workarounds

Manually tighten filesystem permissions on Pardus-Parental-Control critical resources so only root can write
Enforce immutable attributes on /etc/resolv.conf and /etc/hosts using chattr +i where operationally feasible
Limit local logon rights on shared or child-user endpoints to reduce the pool of accounts able to trigger the flaw

bash

# Configuration example: restrict permissions and verify installed version
sudo chown root:root /etc/pardus-parental-control/
sudo chmod 700 /etc/pardus-parental-control/
sudo chmod 644 /etc/resolv.conf /etc/hosts
sudo chattr +i /etc/resolv.conf
dpkg -l | grep pardus-parental-control