VulnerabilityPublished 22 Sep 2026

CVE-2026-77556: Ubiquiti Dream Machines · Out-of-bounds Read

Affects Ubiquiti Dream MachinesSource CVE Database V5

Compare

Not known to be exploited · CVSS 7.5 High : upgrade to 5.1.31 soon.

Data as of 5 Nov 2026, 23:24 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 5.1.31, 4.0.21, 5.1.26

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Dream Machines and Enterprise Firewalls and Dream Routers and Cloud Gateways and Dream Wall and Express 7 to 5.1.31; Express to 4.0.21; UniFi Gateways to 5.1.26.

Affected software

Product	Affected	Fixed in
Ubiquiti IncDream Machines	Affected <5.1.31	Fixed in 5.1.31
Ubiquiti IncEnterprise Firewalls	Affected <5.1.31	Fixed in 5.1.31
Ubiquiti IncDream Routers	Affected <5.1.31	Fixed in 5.1.31
Ubiquiti IncCloud Gateways	Affected <5.1.31	Fixed in 5.1.31
Ubiquiti IncDream Wall	Affected <5.1.31	Fixed in 5.1.31
Ubiquiti IncExpress	Affected <4.0.21	Fixed in 4.0.21

AI-suggested

If you cannot patch yet, restricting network access to trusted users and devices may reduce exposure.

Description

CVE-2026-77556 is an out-of-bounds read vulnerability in Ubiquiti Inc's Dream Machines UniFi gateway devices. This flaw allows a network-based attacker to cause a denial of service (DoS) by exploiting the memory access error. The vulnerability does not impact confidentiality or integrity but results in service disruption. It affects multiple versions prior to 5.1.31, 4.0.21, and 5.1.26. No known exploits are reported in the wild. The CVSS score is 7.5, indicating high severity.

Impact

Successful exploitation results in denial of service (device crash or unavailability). There is no impact on confidentiality or integrity. The attack requires network access but no privileges or user interaction.

Summary

This vulnerability (CWE-125) involves an out-of-bounds read in Ubiquiti Dream Machines UniFi gateway devices. An attacker with network access can trigger this flaw to cause a denial of service condition, disrupting device availability. The vulnerability affects versions prior to 5.1.31, 4.0.21, and 5.1.26. There is no indication of confidentiality or integrity impact. No vendor patch links are provided in the data, and no known exploits have been observed.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

community.ui.com/releases/Security-Advisory-Bulletin-069-069/07e367a7-edec-4d85-a058-f97e5ce9ac9c (opens in a new tab)

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Sep 2026, 20:46 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

Related threats