Widely used UniFi OS devices; auth bypass could grant admin control across many networks.
CVE-2026-54403
Path traversal allows authentication bypass on UniFi OS.
Is CVE-2026-54403 being exploited?
Not confirmed. CVE-2026-54403 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.77% probability of exploitation in the next 30 days.
How severe is CVE-2026-54403?
CVE-2026-54403 is rated High with a CVSS score of 8.6. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-54403?
Yes. A fix has been recorded for CVE-2026-54403. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-54403 affect?
CVE-2026-54403 affects UniFi OS devices. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-54403?
Apply firmware/patch when released; implement segmentation and monitor admin interfaces.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
LAN attacker can bypass login to gain admin control of UniFi OS devices.
Patch when possible
- affected< 5.1.19
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As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.