CVE-2026-80302Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate unrestricted file upload
CVE-2026-80302 is a unrestricted file upload in Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, rated high (8.8 on CVSS 3.1).
Why this priority: High severity, with no exploitation signal yet.
Published · Updated · NVD status: Received
What it is
Files of dangerous types can be uploaded, and the server may run or serve them.
How it is reached
An attacker can exploit it by someone who can already run code or sign in on the machine, with an ordinary user account, and nobody has to click anything.
What an attacker gains
A successful attack can read the data it protects, change data or behaviour and take it offline. In practice, this kind of flaw lets an attacker place a file the server will run or serve to others. The damage can spread past the vulnerable component into others.
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 to 26.7 or later. Other affected products have their own fixed versions on this page.
- Limit who can run code or sign in on the hosts that run it.
Description from NVD
Insufficient isolation in the Avast sandbox file virtualization layer on Windows allows a local, low-privileged attacker executing inside the sandbox to write arbitrary files outside sandbox containment and execute code on the host.
The sandbox virtualizes file system operations by intercepting write requests to protected system directories. However, the virtualization implementation fails to properly validate write targets in certain edge cases, allowing writes to bypass the virtualization redirection and reach the actual host file system in protected locations.
An attacker can exploit this to overwrite executable files, system libraries, or startup configurations with arbitrary content, leading to code execution with host privileges on subsequent system operations or reboot.
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
- Upload endpoints and the storage behind them. The flaw sits between uploaded content and the servers that store or serve it.
Trust boundaries in play
- Host boundary. The attacker needs a foothold on the machine first; the flaw turns a small foothold into a bigger one.
- Isolation between components. The impact crosses out of the vulnerable component into others it should be isolated from.
- Between uploaded content and the servers that store or serve it. An attacker who crosses it can place a file the server will run or serve to others.
Questions to answer about your own systems
- Where does Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate run in your systems, and at which version?
- Which of those hosts also run code or users you do not fully trust?
- 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.