CVE-2026-77548

Executive Summary

CVE-2026-77548 is an Improper Input Validation vulnerability (CWE-20) in the UniFi Protect Application that enables Command Injection on the host device. A malicious actor with network access and low-privilege credentials can exploit this flaw to achieve remote code execution with the privileges of the application process. With a CVSS v3.1 base score of 9.9, the vulnerability is rated critical due to its network reachability, low complexity of exploitation, and full impact on confidentiality, integrity, and availability across a security-scope change. At the time of writing, no vendor patch, workaround, or public exploit has been identified, leaving all deployments of UniFi Protect Application potentially exposed.

Technical Analysis

Vulnerability Mechanism

The root cause of CVE-2026-77548 is an Improper Input Validation flaw (CWE-20) within the UniFi Protect Application. The NVD description indicates that an attacker who has network access and holds low-privileged credentials can trigger the vulnerability to execute a Command Injection attack on the underlying host operating system.

Command Injection vulnerabilities occur when an application constructs operating system commands that incorporate user-controlled input without adequate sanitization or validation. In this case, the UniFi Protect Application presumably passes attacker-controlled data — potentially via API endpoints, web request parameters, or other input vectors — into a system command execution context (e.g., shell invocation) without properly validating or escaping the input. This allows an attacker to inject additional shell metacharacters or commands that are then executed by the host.

Attack Surface

The attack surface is the UniFi Protect Application, a video surveillance management platform deployed by Ubiquiti. The application is typically deployed as a service on UniFi hardware (e.g., UniFi Dream Machine Pro, Cloud Key Plus) or as standalone software on Linux-based hosts. Because the application is network-facing and commonly accessible over the internet for remote video monitoring, any unauthenticated or low-privileged user with network reachability to the application's management interfaces could attempt exploitation.

The requirement for low privileges (PR:L) narrows the attack scope slightly — the attacker must already have some level of authenticated access to the UniFi Protect system. This could be a legitimate but restricted user account (e.g., a viewer-only account) or a compromised low-privilege credential. However, the CVSS vector indicates the attack is network-based (AV:N) and requires no user interaction (UI:N), meaning an authenticated low-privilege user can trigger the flaw remotely.

Technical Details (Class-Level Analysis)

The NVD description does not identify the specific function, endpoint, or parameter that is vulnerable, nor does it disclose the command injection payload structure. Insufficient technical detail is available to identify precise code paths or affected API routes. The vulnerability is characterized at the class level as CWE-20 (Improper Input Validation) leading to OS Command Injection (CWE-78 — Improper Neutralization of Special Elements used in an OS Command). Attackers would likely exploit this by supplying specially crafted input strings that include shell metacharacters (e.g., ;, |, &&, backticks, $()), which the application then passes to a system call such as system(), popen(), or an equivalent shell invocation.

Security Scope and Impact

The CVSS vector includes S:C (Scope: Changed), indicating that the vulnerability compromises components beyond the initially impacted system boundary. This suggests that a successful exploit could allow the attacker to pivot from the application context to the host operating system and potentially the broader network infrastructure. Combined with the high Confidentiality (C:H), Integrity (I:H), and Availability (A:H) impacts, a fully exploited CVE-2026-77548 could result in complete compromise of the UniFi Protect host device and the data it processes, including video surveillance footage, configuration data, and network access credentials.

Exploitation Scenarios

No public PoC or exploit code is available for CVE-2026-77548 as of this analysis. The attack chain described below is inferred from the vulnerability class (Improper Input Validation leading to Command Injection) and the CVSS characteristics indicated in the CVE data. Specific command names, API endpoints, or payload structures are not known.

Step 1 — Reconnaissance and Target Identification:

An attacker would first identify internet-exposed UniFi Protect instances. Shodan queries such as title:"UniFi Protect" or "UniFi Protect" server can enumerate hosts running the application. The attacker would then attempt to authenticate with low-privileged credentials — possibly obtained via credential stuffing, phishing, or previous breach of the organization's credentials. Alternatively, if any default or weak credentials exist on the UniFi Protect instance, they could be leveraged.

Step 2 — Triggering the Input Validation Flaw:

Once authenticated with a low-privilege account, the attacker would interact with UniFi Protect's application functionality that processes user-supplied input. Because CWE-20 is a broad classification, candidate attack vectors include:

• Crafting HTTP API requests with malicious parameters in URLs, headers, or POST bodies.
• Submitting specially crafted data through web form fields.
• Manipulating file names, device names, or other configuration fields that the application stores and later uses in system commands.

Since no specific endpoint is disclosed in the NVD data, the attacker may probe various input fields to identify which one is passed to an underlying system command without validation.

Step 3 — Payload Execution:

At the vulnerability-class level, the attacker would submit input containing shell metacharacters or command substitution strings. The UniFi Protect Application, lacking proper input validation, would concatenate or interpolate these inputs into a command executed by the host operating system. For example, if the application constructs a command to restart a service, generate a report, or process media based on attacker-controlled data, the injected payload would execute in addition to the intended command. The attacker could execute arbitrary OS commands, download and run additional malware, create new user accounts, or exfiltrate sensitive files.

Step 4 — Post-Exploitation Impact:

Successful exploitation results in command execution on the host device with the privileges of the UniFi Protect process — typically root or a high-privilege service account on the underlying host. The attacker could:

• Extract credentials from configuration files or the application database.
• Access recorded surveillance video footage, potentially compromising physical security.
• Use the compromised host as a pivot point for lateral movement into the internal network (consistent with the CVSS Scope: Changed).
• Disable the UniFi Protect service, disrupting surveillance capabilities (Availability impact).
• Persist by planting backdoors, modifying system files, or creating scheduled tasks.

The full Confidentiality, Integrity, and Availability impacts align with the CVSS components (C:H/I:H/A:H).

Impact Assessment

Critical Severity (CVSS 9.9). CVE-2026-77548 represents a critical risk to organizations deploying UniFi Protect Application. The attack requires only low-privileged network access, is exploitable remotely over the network, and requires no user interaction. The resulting command injection provides full system compromise.

Business Impact:

• Physical Security Compromise: UniFi Protect is a video surveillance system. Command injection could allow an attacker to access, delete, or manipulate video footage, potentially covering up physical intrusions or facilitating corporate espionage.
• Data Breach: The host device contains surveillance video, system configuration, and potentially network credentials. Full system access enables exfiltration of all these data types.
• Lateral Movement: The Scope: Changed (S:C) indicator coupled with host-level access makes lateral movement into the internal network highly probable, extending the blast radius well beyond the UniFi device.
• Availability: An attacker can shut down or disable the surveillance system, creating operational blind spots.

Affected Systems: Any deployment of the UniFi Protect Application. Since no specific version range is identified in the NVD data, and no patch exists, all current deployments are presumed vulnerable. This includes UniFi OS-based appliances (e.g., Dream Machine series, Cloud Key Plus) and self-hosted installations on Linux servers.

Blast Radius: The host device and, by extension, the entire network segment reachable from that host. Given the command injection nature, any service accessible from the compromised host is at risk.

Detection Guidance

Sigma Rule

title: Suspicious Command Execution via UniFi Protect Application
id: 6f5c3a2e-9d1b-4c7a-8e5f-2a1b3c4d5e6f
status: experimental
description: Detects potential command injection attempts targeting CVE-2026-77548 in UniFi Protect Application, based on suspicious shell metacharacters in web request parameters.
author: Valters IT Threat Intelligence
date: 2026/11/15
logsource:
  category: webserver
  product: nginx
  definition: 'Requires UniFi Protect access logs capturing HTTP requests'
detection:
  selection_shell_chars:
    c-uri|contains:
      - '%3B'        # URL-encoded semicolon
      - '%7C'        # URL-encoded pipe
      - '%26'        # URL-encoded ampersand
      - '%24%28'     # $(
      - '%60'        # backtick
  selection_auth:
    cs-uri-stem|contains:
      - '/api/'
      - '/proxy/protect/'
  condition: selection_shell_chars and selection_auth
  timeframe: 5m
level: high
falsepositives:
  - Legitimate URL-encoded characters in filenames or search queries
  - URL encoding required for international characters
fields:
  - c-ip
  - cs-uri-query
  - cs-username
tags:
  - attack.t1190
  - attack.execution
  - cve.2026-77548
  - command.injection

YARA Rule

rule CVE_2026_77548_UniFi_Protect_Command_Injection
{
    meta:
        author = "Valters IT Threat Intelligence"
        description = "Detects exploit payload patterns for CVE-2026-77548 UniFi Protect Command Injection"
        date = "2026-11-15"
        cve = "CVE-2026-77548"
        severity = "critical"

    strings:
        $s1 = ";id;" ascii nocase
        $s2 = ";whoami;" ascii nocase
        $s3 = "$(id)" ascii nocase
        $s4 = "$(whoami)" ascii nocase
        $s5 = "|id" ascii nocase
        $s6 = "`id`" ascii nocase
        $s7 = "&& whoami" ascii nocase
        $s8 = ";/bin/sh" ascii nocase
        $s9 = "curl " ascii nocase
        $s10 = "wget " ascii nocase
        $s11 = "unifi" ascii nocase
        $s12 = "protect" ascii nocase

    condition:
        uint16(0) == 0x0A0D or uint32(0) == 0x0A0D0A0D or filesize > 100KB
        and 2 of ($s1, $s2, $s3, $s4, $s5, $s6, $s7, $s8)
        and 1 of ($s9, $s10)
        and 1 of ($s11, $s12)
        or (1 of ($s1, $s2, $s3, $s4, $s5, $s6, $s7, $s8) and 1 of ($s11, $s12))
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-77548 Attempted Command Injection in UniFi Protect Application"; flow:established,to_server; content:"GET"; http_method; content:"/proxy/protect/"; http_uri; nocase; pcre:"/(?:;|\||&|`|\$\().*(?:id|whoami|uname|cat|curl|wget|nc|bash|sh)/Ui"; reference:cve,2026-77548; classtype:attempted-admin; sid:777548001; rev:1; metadata:created_at 2026_11_15, updated_at 2026_11_15;)

Note: This Suricata rule inspects HTTP requests for shell metacharacters combined with common Linux enumeration/exploitation commands. Adjust destination ports to match UniFi Protect deployment (typically 443 for web interface).

Elastic Detection

sequence by host.name with maxspan=5m
  [network where event.type == "start" and destination.port in (443, 7443) and
     process.name == "nginx" and
     network.protocol == "http"] // connection to UniFi Protect
  [http where event.action == "request" and
     url.path contains "/proxy/protect/" and
     (
       url.query contains (";", "|", "&&", "$(", "`") or
       any(user_agent, process.command_line, url.original) matches
         ".*(;id;|;whoami;|\\$\\(id\\)|\\$\\(whoami\\)|\\|cat|\\|nc ).*"
     ) and
     http.request.method in ("GET", "POST", "PUT")]

Splunk SPL Query

index=web sourcetype=access_combined uri_path="/proxy/protect/*"
  OR uri_path="/api/*"
  (uri_query IN ("*%3B*", "*%7C*", "*%26*", "*%24%28*", "*%60*")
  OR uri_query IN ("*;*", "*|*", "*&&*", "*$( *", "*`*"))
  AND (uri_query IN ("*id*", "*whoami*", "*cat*", "*curl*", "*wget*", "*bash*", "*sh*"))
| stats count by src_ip, uri_path, uri_query, status, user, _time
| sort - _time
| rename src_ip as "Source IP", uri_path as "Request Path", uri_query as "Query String"

Wazuh OSSEC Rule

<group name="web,command_injection,cve-2026-77548,">
  <rule id="775480" level="12" frequency="5" timeframe="60">
    <if_matched_sid>30601, 31100, 31101, 31122</if_matched_sid>
    <match>%3B|%7C|%26|%24%28|%60|;|&&|\$\(|`</match>
    <regex>\/proxy\/protect\/|\/api\/</regex>
    <description>CVE-2026-77548 - Possible Command Injection attempt against UniFi Protect Application</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>attack.execution,</group>
  </rule>

  <rule id="775481" level="10">
    <if_sid>775480</if_sid>
    <match>id=|whoami|uname|cat /etc/passwd</match>
    <description>CVE-2026-77548 - Command injection payload contains reconnaissance commands</description>
    <group>attack.discovery,</group>
  </rule>

  <rule id="775482" level="14">
    <if_sid>775480</if_sid>
    <match>curl|wget|nc -e|bash -i</match>
    <description>CVE-2026-77548 - Command injection payload contains exploit/download commands</description>
    <group>attack.execution,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED. No vendor patch, security advisory, or fixed version has been identified from any tracked source as of this report's compilation. The Patch Sources and Vendor Fix fields in the CVE data are empty, and the affected version list is blank, indicating insufficient vendor communication regarding remediation.

Immediate Mitigations (in order of effectiveness):

1. Restrict Network Access: Limit access to the UniFi Protect Application's management interface to trusted internal networks only. If remote access is required, enforce VPN access rather than direct internet exposure. Use firewall rules to block external access to UniFi Protect web/management ports (default HTTPS 443, but consult deployment docs).
2. Enforce Least Privilege: Review all UniFi Protect user accounts. Remove or downgrade any low-privileged accounts where possible. Enable multi-factor authentication (MFA) on all accounts. Strictly audit and rotate credentials, especially for accounts that have access to the Protect application from non-admin levels.
3. Monitor for Suspicious Activity: Deploy the detection rules provided in this report across SIEM, IDS/IPS, and EDR systems to detect potential exploitation attempts.
4. Disable Unnecessary Features: If the UniFi Protect application provides SSH access, remote management features, or other exposed services, disable them unless required for operations.

Patch/Upgrade Steps:

• Monitor Ubiquiti's official security advisories at https://community.ui.com/releases and https://www.ui.com/ for announcements related to CVE-2026-77548.
• Subscribe to Ubiquiti's security notification mailing list.
• When a patched version of UniFi Protect Application is released, schedule an immediate upgrade during a maintenance window. Test the upgrade in a staging environment first if feasible.
• Additionally, ensure the underlying UniFi OS or operating system is updated with the latest vendor patches.

Long-Term Hardening:

• Segmentation: Place UniFi Protect devices and their management interfaces on a dedicated VLAN or network segment with strict egress and ingress controls. Isolate the surveillance network from general corporate traffic.
• Credential Management: Implement a robust identity management solution. Enforce strong password policies, MFA, and periodic credential rotation for all UniFi Protect accounts.
• Continuous Monitoring: Maintain the detection rules provided above in production monitoring systems. Regularly tune and update them based on emerging threat intelligence.
• Backup and Recovery: Ensure configuration backups and video footage backups (if retention is required) are stored separately and encrypted. Test restore procedures.
• Vendor Relationship: Maintain active communication with Ubiquiti for security advisories. Since this CVE is unpatched, proactive outreach to the vendor or their support channels regarding a fix timeline is advisable.

References

1. NVD Entry for CVE-2026-77548: https://nvd.nist.gov/vuln/detail/CVE-2026-77548 — Official NIST National Vulnerability Database record with the vulnerability description and CVSS scoring.
2. Ubiquiti Security Advisories/Releases: https://community.ui.com/releases — Monitor for patch announcements and security bulletins from the vendor (Ubiquiti). As of writing, no specific advisory for this CVE has been published.
3. CWE-20 Improper Input Validation: https://cwe.mitre.org/data/definitions/20.html — MITRE Common Weakness Enumeration entry describing the vulnerability class.
4. CWE-78 Improper Neutralization of Special Elements used in an OS Command: https://cwe.mitre.org/data/definitions/78.html — Related CWE class for the command injection mechanism resulting from CVE-2026-77548.
5. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog — Confirmed: CVE-2026-77548 is not currently listed in the KEV catalog.

Known Threat Actor Campaigns or Exploit-in-the-Wild Evidence: None identified. There is no evidence of active exploitation of CVE-2026-77548 in the wild at the time of this report. The EPSS score has not yet been assigned by FIRST.org, further indicating the recent disclosure of this vulnerability and the absence of exploitation data.