CVE-2026-123033: IXsystems TrueNAS SCALE authentication bypass…

Q: Is CVE-2026-123033 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Q: What does this mean?

A flaw in the origin check of the HA heartbeat in middlewared lets an attacker bypass authentication and gain unauthenticated full administrator access to the API. From there they can read configuration secrets and lead to command execution as root. The attacker must be on the same layer-2 segment as the management interface and must also alter the return path, by changing routing on the TrueNAS system or controlling the gateway or path.

Q: Am I affected, and how do I check?

TrueNAS SCALE releases before 25.10.8 are affected, and the advisory says the hook is registered on all installations, including non-HA single-node Community Edition systems. To check a system, compare its installed TrueNAS SCALE version with 25.10.8.

Q: How do I fix CVE-2026-123033?

Upgrade to TrueNAS SCALE 25.10.8 or a later release in the 25.10 train, which contains the fix.

Summary

An authentication bypass in the high-availability heartbeat check of middlewared, the management service in TrueNAS SCALE, lets an attacker on the same network segment gain unauthenticated full-administrator API access and run commands as root. The flawed authentication hook is also active on single-node Community Edition systems without HA, and exploiting it requires no login or user action.

Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.

Read the original description

Authentication bypass in the HA heartbeat origin check in middlewared in TrueNAS SCALE before 25.10.8 (and in release trains before their respective fixes) allows an attacker on the same network segment to achieve unauthenticated full-administrator API access and execute commands as root. middlewared registers the HA peer-authentication hook (ha_permission) unconditionally, with no failover-licence or heartbeat-interface check. An unauthenticated connection whose TCP peer address is a hardcoded HA heartbeat address (169.254.10.1 or 169.254.10.2) and whose peer port is <= 1024 is granted a node credential that is authorized for every API method and treated as full administrator. Both conditions are properties of the attacker's own socket, and thus an attacker on the same layer-2 segment satisfies them without forging anything. The hook is present on non-HA, unlicensed, single-node Community Edition installations. The fix additionally requires that the connection terminate on the HA heartbeat listener (a local address/port the attacker cannot control).

cve.now Index

8Pcve.now Index 8 of 100 · methodology v3 · provisional

Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
Exposure?/25Unknown. Advisories don't say whether default setups are affected
Reach?/20Unknown. No tracked technology or package matched
Severity8.3/10CVSS 8.3
No patch0/5No signal

What would change the score

Would score about 63 if added to CISA KEV
Would score about 58 if CISA's SSVC rates exploitation active
Would score about 30 if advisories confirm default setups are exposed

How the score works · Leaderboard

What to do

Upgrade to a fixed version: 25.10.8.
Workaround: Keep the TrueNAS management interface on a dedicated, trusted management network and ensure no untrusted host shares its layer-2 segment

Timeline

Nov 5, 2026, 6:58 AM UTCCVE published
Nov 5, 2026, 7:02 AM UTCFirst seen by cve.now

Affected versions

iXsystems TrueNAS SCALE
fixed in 25.10.8

Evidence 1

Link
security.truenas.com · scale/impact-statements/ha-node-auth-bypass

Corrections

None so far.

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Questions about CVE-2026-123033

Is CVE-2026-123033 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

What does this mean?

A flaw in the origin check of the HA heartbeat in middlewared lets an attacker bypass authentication and gain unauthenticated full administrator access to the API. From there they can read configuration secrets and lead to command execution as root. The attacker must be on the same layer-2 segment as the management interface and must also alter the return path, by changing routing on the TrueNAS system or controlling the gateway or path.Source: security.truenas.com

Which versions are affected by CVE-2026-123033?

TrueNAS SCALE: before 25.10.8.Source: cve.now feed data

Am I affected, and how do I check?

TrueNAS SCALE releases before 25.10.8 are affected, and the advisory says the hook is registered on all installations, including non-HA single-node Community Edition systems. To check a system, compare its installed TrueNAS SCALE version with 25.10.8.Source: security.truenas.com

How do I fix CVE-2026-123033?

Upgrade to TrueNAS SCALE 25.10.8 or a later release in the 25.10 train, which contains the fix.Source: security.truenas.com

Authentication bypass in the HA heartbeat origin check in middlewared in TrueNAS SCALE before 25.10.8 (and in release trains before their…