CriticalCISA KEVExploited in the wildPublic exploit

Ubiquiti UniFi OS Command Injection via Improper Input Validation

IdentifiersCVE-2026-34910CWE-20· Improper Input Validation

CVE-2026-34910 is a critical improper input validation vulnerability in Ubiquiti UniFi OS, including UniFi OS Server, that allows command injection. Available reporting indicates the flaw is in the package-update service/endpoint, where attacker-controlled package name input is insufficiently validated and is interpolated into a shell command. Bishop Fox reported the vulnerable backend constructed a command similar to "sudo /usr/bin/uos runnable latest-versions %v" and executed it through an "sh -c" wrapper, allowing shell metacharacter injection. The issue can be exploited by a malicious actor with network access, and in practice has been shown as the command-execution stage of a larger exploit chain with CVE-2026-34908 and CVE-2026-34909 to achieve unauthenticated remote code execution against exposed UniFi OS management interfaces.

For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

Start free trial

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows arbitrary operating system command execution on the affected UniFi OS device. Reporting indicates the injected commands initially execute as the ucs-update service account, but that account has passwordless sudo access to sensitive binaries such as /usr/bin/dpkg, /usr/bin/uos, /bin/systemctl, and /bin/chmod on affected systems, making escalation to full root compromise trivial. In chained exploitation, this can result in unauthenticated remote code execution with full root privileges, theft of secrets, persistence, forged administrative sessions, lateral movement, and complete takeover of the UniFi management plane and managed infrastructure.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, restrict or eliminate exposure of the UniFi OS management interface from untrusted networks, especially internet exposure of the web interface commonly reachable on TCP 11443. Limit network adjacency to trusted administrative paths only. Increase monitoring for requests involving /api/auth/validate-sso/ with encoded traversal sequences and access to package-update routes such as ucs/update/latest_package, as these may indicate chaining activity. Because attackers may obtain root and tamper with logs, rely on external telemetry where possible. If compromise is suspected, rotate host- and application-level secrets, including signing keys, tokens, TLS keys, and credentials, since patching alone does not invalidate previously stolen material.

Remediation

Patch, then assume compromise.

Upgrade affected systems to vendor-fixed releases. For UniFi OS Server, multiple sources in the provided content state that Ubiquiti fixed CVE-2026-34910 in UniFi OS Server 5.0.8 or later. Broader UniFi OS device families should be updated to the vendor-fixed versions identified in Ubiquiti Security Advisory Bulletin 064 for the relevant platform. The fix reportedly includes package-name validation and removal of shell-based execution in the backend, along with related hardening. Because active exploitation has been reported and patching does not remediate prior compromise, organizations should also investigate for compromise and rebuild from known-good images where appropriate.

PUBLIC EXPLOITS

Exploits

No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.

VALID 0 / 1 TOTALView more in app

All candidate exploits were filtered out by Mallory's validation.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

UbiquitiUnifi Osapplication

UbiquitiUnifi Os Serveroperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

46 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

46 SOURCESView more in app

cyberthroneNews

Jun 26, 2026

CISA’s KEV Wave: Ubiquiti, Lantronix, and Cisco Unified CM Join the List - TheCyberThrone

An improper input validation vulnerability in Ubiquiti UniFi OS that enables OS command injection and arbitrary code execution.

cysecurity newsNews

Jun 25, 2026

Ubiquiti UniFi OS Flaw Under Active Exploitation CISA Alerts Users - CySecurity News - Latest Information Security and Hacking Incidents

A command injection vulnerability in Ubiquiti UniFi OS that allows arbitrary operating system command execution, potentially without authentication when chained with the UniFi OS bypass flaws.

the hacker newsNews

Jun 24, 2026

CISA Warns Critical Lantronix EDS5000 Flaw Is Being Actively Exploited

An improper access control vulnerability in Ubiquiti UniFi OS that can allow a malicious actor with network access to make unauthorized changes to the system. It is part of a three-vulnerability RCE chain.

security weekNews

Jun 24, 2026

Critical Ubiquiti Vulnerabilities in Attackers' Crosshairs - SecurityWeek

A critical improper input validation vulnerability in Ubiquiti UniFi OS that enables network-based command injection. It can be reached via the authentication bypass associated with CVE-2026-34908 and CVE-2026-34909, enabling unauthenticated exploitation.

+12 more in the timeline

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

Start free trial

Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware3

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity27

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-34910

NVD

nvd.nist.gov/vuln/detail/CVE-2026-34910

MITRE CWE · CWE-20

Improper Input Validation

community.ui.com

community.ui.com/releases/Security-Advisory-Bulletin-064-064/84811c09-4cf4-42ab-bd61-cc994445963b