CVE-2026-63442Public exploit

DoS and lockout bypass via forged logs

Published Oct 15, 2026 · Updated Oct 15, 2026

Log injection in OPNsense Core before 26.1.11 allows remote attackers to block IP addresses via WebGUI login usernames. Unsanitized carriage returns and line feeds pass through syslog-ng to lockout_handler, whose readline() processing interprets injected fragments as authentication events and selects an attacker-specified IP address. Network access to the login page is sufficient under the default configuration to terminate that IP's active firewall states and block traffic, or reset password-guessing counters with forged accepted events.

CVSS severity8.1
High
EPSS probability0.29%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Log injection in OPNsense Core before 26.1.11 allows remote attackers to block IP addresses via WebGUI login usernames. Unsanitized carriage returns and line feeds pass through syslog-ng to lockout_handler, whose readline() processing interprets injected fragments as authentication events and selects an attacker-specified IP address. Network access to the login page is sufficient under the default configuration to terminate that IP's active firewall states and block traffic, or reset password-guessing counters with forged accepted events.

The record

CVE
CVE-2026-63442
Published
Oct 15, 2026
Updated
Oct 15, 2026
Vendor
OPNsense
Product
OPNsense Core
Classifications
CWE-117, T1562.001
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 26.1.11

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

OPNsense · OPNsense Coreversion=< 26.1.11

Published CVSS scores

8.1GitHub_MCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-117Improper Output Neutralization for Logs
T1562.001Disable or Modify Tools

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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