OPNsense: Log Forgery via Login Username CRLF in WebGUI Authentication → Pf Table IP Blocking
CVSS score
8.1
EPSS probability
—
Risk score
0.8
Published
3 h ago
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Impact on My Inventory
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Vulnerability description
CVE AI research
DayBreach AI Explanation
Verified against sourcesSources read
2
Source agreement
Tam uyum
Evidence confidence
%63
Short explanation
This vulnerability in OPNsense allows unauthenticated users to inject CRLF characters into the login username field and forge logs. Attackers can leverage this to add target IP addresses to the sshlockout PF table or reset brute-force counters.
This flaw allows attackers to block administrative, DNS, gateway, or monitoring IP addresses and bypass password-guessing lockouts without authentication.
What should be done?
- Follow vendor advisories and updates
- Update the OPNsense core
Chain of evidence and sources
OPNsense WebGUI giriş kullanıcı adı alanında CRLF karakterleri işlenerek log sahteciliği yapılabilir.
Saldırganlar bu açığı kullanarak başka bir IP için başarısızlık olayları sahte olarak üretebilir ve bu IP'nin sshlockout PF tablosuna eklenmesine neden olabilir.
Show the technical text from the sources
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.
CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
CWE: CWE-117
Explanation produced with the local gemini-flash-lite-latest model. Numerical metrics and the KEV, patch and exploit statuses are not determined by AI.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-63442 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | opnsense | core | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 8.1 | CVSS V31 | HIGH | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H | NVD |
| 8.1 | CVSS V3_1 | HIGH | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H | CVE CNA |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-63442 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-63442 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
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