CVE-2026-4266
MediumCVSS 6.7Exploitation Probability (EPSS)
Low risk19th percentile - higher than 19% of all known CVEs
Summary
An Insecure Deserialization vulnerability in WatchGuard Fireware OS allows an attacker with write access to the local filesystem to execute arbitrary code in the context of the portald user. This does not affect Firebox platforms without Access Portal support, including T15 and T35.
Risk Assessment
An attacker can execute arbitrary code on the device, potentially leading to full device and network compromise.
Recommendation
Apply WatchGuard Fireware OS updates and restrict access to the local filesystem.
Other vulnerabilities in WatchGuard Fireware OS
See all- CVE-2026-93866Critical
An integer overflow vulnerability exists in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal. A remote, unauthenticated attacker can write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled.
- CVE-2026-93865Critical
A missing authentication vulnerability exists in the Fireware OS FireCluster synchronization daemon. A remote, unauthenticated attacker can invoke privileged system-level administrative actions by sending a specially crafted request to the FireCluster management IP when the clustering feature is enabled.
- CVE-2026-93857Critical
A stack-based buffer overflow vulnerability exists in Fireware OS's SIP proxy. A remote, unauthenticated attacker can execute arbitrary code by sending a specially crafted request through a policy that uses the SIP proxy.
- CVE-2026-90465Critical
A missing authentication vulnerability exists in FireCluster Sync processing. An attacker positioned on the cluster interconnect, such as a compromised cluster peer or an on-path network attacker, can invoke privileged firewall management actions as root by sending a specially crafted request.
- CVE-2026-112710Critical
A heap-based buffer overflow vulnerability exists in the Fireware OS authentication service. An attacker who controls or intercepts traffic to the configured Active Directory server can create a denial of service condition and potentially execute arbitrary code by returning a specially crafted response.
- CVE-2026-112709Critical
A heap-based buffer overflow vulnerability exists in the Fireware OS authentication service. An attacker who controls or intercepts traffic to the configured Active Directory server can create a denial of service condition and potentially execute arbitrary code by returning a specially crafted response.
- CVE-2026-103594Critical
A stack-based buffer overflow vulnerability exists in Fireware OS's WireGuard configuration processing. A remote attacker with man-in-the-middle TLS-decrypted access between the Firebox and WatchGuard Cloud can create a denial of service condition and potentially execute arbitrary code by tampering with a FireCloud Gateway configuration payload.
- CVE-2026-86131Critical
A code injection vulnerability in WatchGuard Fireware OS's BOVPN Over TLS client configuration handling allows an attacker who controls the remote VPN server to execute arbitrary commands as root on the connecting Firebox.
- CVE-2026-19318Critical
A stack-based buffer overflow in the iked process of WatchGuard Fireware OS allows a remote unauthenticated attacker to execute arbitrary code by sending specially crafted network traffic.
- CVE-2026-19315Critical
A type confusion vulnerability in the iked process of WatchGuard Fireware OS allows a remote unauthenticated attacker to execute arbitrary code by sending specially crafted network traffic.
Original NVD description (English source)
An Insecure Deserialization vulnerability in WatchGuard Fireware OS allows an attacker that has obtained write access to the local filesystem through another vulnerability to execute arbitrary code in the context of the portald user. Note, this vulnerability does not affect Firebox platforms that do not support the Access Portal feature, including the T15 and T35.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

