CVE-2026-71490
Received Received - Intake

Privilege Escalation in OPNsense Firewall

Publication date: 2026-10-15

Last updated on: 2026-10-15

Assigner: GitHub, Inc.

Description
OPNsense is a FreeBSD based firewall and routing platform. Prior to 26.1.11, OPNsense\Core\ACL::hasPrivilege() appends a directly assigned comma-separated <priv> value as one string and then uses an exact comparison when checking user-config-readonly. A user directly assigned both a component write privilege and user-config-readonly can therefore be treated as lacking the read-only restriction, and MVC APIs protected by throwReadOnly() can persist configuration changes for that component. Group privileges are not affected by the same parser flaw because the group path already splits comma-separated values. This issue is fixed in version 26.1.11.

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Meta Information

Published
2026-10-15
Last Modified
2026-10-15
Generated
2026-10-15
AI Q&A
2026-10-15
EPSS Evaluated
N/A
NVD
CVE-2026-71490
EUVD
EUVD-2026-102140

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
opnsense core < 26.1.11

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

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Executive Summary

CVE-2026-71490 is a privilege escalation flaw in OPNsense's ACL system. The hasPrivilege() function incorrectly handles comma-separated privilege strings for direct user assignments. Instead of splitting and validating each privilege separately, it treats the entire string as one value. This allows a user with both component write privileges and user-config-readonly to bypass read-only restrictions and make unauthorized configuration changes.

Detection Guidance

To detect CVE-2026-71490, check the OPNsense version installed on your system. If it is below 26.1.11, the system is vulnerable. Run 'pkg info os-core' on OPNsense to verify the version. Additionally, inspect the ACL.php file in the OPNsense Core for the hasPrivilege function to confirm if it properly splits comma-separated privileges.

Impact Analysis

This vulnerability allows attackers with limited privileges to escalate their access and make unauthorized changes to system configurations. It could lead to persistent modifications of firewall rules, network settings, or other critical components despite being assigned read-only restrictions. The impact depends on the specific privileges granted to the compromised account.

Mitigation Strategies

Immediately upgrade OPNsense to version 26.1.11 or later to patch the vulnerability. If upgrading is not immediately possible, restrict user privileges to prevent assigning both component write and user-config-readonly privileges simultaneously. Review user privilege assignments to ensure no unauthorized configuration changes can occur.

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