OPNsense up to 26.1.10 SSL Certificate Selector system_advanced_admin.php legacy_html_escape_form_data a_cert cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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3.7$0-$5k0.88+

Summaryinfo

A vulnerability has been found in OPNsense up to 26.1.10 and classified as problematic. Impacted is the function legacy_html_escape_form_data of the file src/www/system_advanced_admin.php of the component SSL Certificate Selector. The manipulation of the argument a_cert leads to cross site scripting. This vulnerability is traded as CVE-2026-58394. It is possible to initiate the attack remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in OPNsense up to 26.1.10. This issue affects the function legacy_html_escape_form_data of the file src/www/system_advanced_admin.php of the component SSL Certificate Selector. The manipulation of the argument a_cert with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. The summary by CVE is:

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, src/www/system_advanced_admin.php reads certificate records into $a_cert but omits that array from legacy_html_escape_form_data() before rendering each certificate descr value in the SSL Certificate selector. The certificate description accepts HTML metacharacters, allowing a user with the page-system-certmanager privilege to store markup that executes when another user opens System Settings Administration. This issue is fixed in version 26.1.11.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-58394 since 06/30/2026. The exploitation is known to be easy. The attack may be initiated remotely. Additional levels of successful authentication are needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

By approaching the search of inurl:src/www/system_advanced_admin.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 26.1.11 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.8
VulDB Meta Temp Score: 3.7

VulDB Base Score: 2.4
VulDB Temp Score: 2.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.2
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Google Hack: 🔒
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: OPNsense 26.1.11

Timelineinfo

06/30/2026 CVE reserved
10/15/2026 +107 days Advisory disclosed
10/15/2026 +0 days VulDB entry created
10/15/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-58394 (🔒)
GCVE (CVE): GCVE-0-2026-58394
GCVE (VulDB): GCVE-100-420689

Entryinfo

Created: 10/15/2026 17:50
Changes: 10/15/2026 17:50 (66)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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