OPNsense up to 26.1.10 WebGUI Login syslog-ng-lockout.conf readline usernamefld injection

CVSS Meta Temp Score
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CTI Interest Score
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7.1$0-$5k0.88+

Summaryinfo

A vulnerability was found in OPNsense up to 26.1.10. It has been classified as critical. The impacted element is the function readline of the file syslog-ng-lockout.conf of the component WebGUI Login. This manipulation of the argument usernamefld causes injection. This vulnerability is handled as CVE-2026-63442. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in OPNsense up to 26.1.10 and classified as critical. Affected by this vulnerability is the function readline of the file syslog-ng-lockout.conf of the component WebGUI Login. The manipulation of the argument usernamefld with an unknown input leads to a injection vulnerability. The CWE definition for the vulnerability is CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. As an impact it is known to affect integrity, and availability. The summary by CVE is:

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the unauthenticated WebGUI login usernamefld accepts carriage-return and line-feed characters that survive LOG_AUTH processing through syslog-ng-lockout.conf into the syslog-ng program destination feeding lockout_handler. The consumer's readline() processing treats an injected fragment as a separate authentication event and selects the first syntactically valid IP address from the forged line. An attacker with network access to the login page can forge failure events for another IP, causing that IP to be added to the sshlockout PF table and its active states to be killed, or forge accepted events that reset an attacker's own brute-force counter. This can block administrative, DNS, gateway, or monitoring addresses and can bypass password-guessing lockout without authentication. This issue is fixed in version 26.1.11.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-63442 since 07/16/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1055 according to MITRE ATT&CK.

Upgrading to version 26.1.11 eliminates this vulnerability.

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Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.1

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 8.1
CNA Vector (GitHub_M): 🔒

CVSSv2info

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

Exploitinginfo

Class: Injection
CWE: CWE-74 / CWE-707 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
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

07/16/2026 CVE reserved
10/15/2026 +91 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-2026-63442 (🔒)
GCVE (CVE): GCVE-0-2026-63442
GCVE (VulDB): GCVE-100-420691

Entryinfo

Created: 10/15/2026 17:52
Changes: 10/15/2026 17:52 (66)
Complete: 🔍
Cache ID: 216::103

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