CVE-2026-12067Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, Avast Busine uncaught exception
CVE-2026-12067 is a uncaught exception in Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, Avast Busine, rated medium (6.5 on CVSS 3.1).
Why this priority: Medium severity, with no exploitation signal.
Published · Updated · NVD status: Received
What it is
An error nobody catches stops the process or request.
How it is reached
An attacker can exploit it over the network, with an ordinary user account, and nobody has to click anything.
What an attacker gains
A successful attack can take it offline. In practice, this kind of flaw lets an attacker exhaust CPU, memory or connections until the service stops answering.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, Avast Busine to 26.7 or later. Other affected products have their own fixed versions on this page.
- Until it is patched, review who holds accounts that can reach it.
Description from NVD
Missing exception handlers in AvastSvc native message dispatcher (ashServ.dll) on Windows allow a local, unprivileged attacker to crash the service by sending specially crafted JSON messages.
The vulnerability spans multiple handler pathways in the RPC-based native message protocol:
* Log_NmSvc.message handler: converts JSON fields to strings without type validation and without exception boundaries. * OpenInSz_NmSvc handler: converts URL and origin fields to strings without type checking, exposing an exception. * OpenInSz_NmSvc.profile handler: converts the profile field to an integer without validation.
In all three cases, the exceptions are not caught by action-specific handlers and propagate up the dispatcher. The common root cause is the absence of try-catch blocks around JSON type conversions in the native message processing chain.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Public entry points and shared services that must stay up. The flaw sits between untrusted traffic and shared capacity.
Trust boundaries in play
- Authenticated network access. An account is needed, so exposure follows who can sign in: customers, partners or staff.
- Between untrusted traffic and shared capacity. An attacker who crosses it can exhaust CPU, memory or connections until the service stops answering.
Questions to answer about your own systems
- Where does Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, Avast Busine run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.