CVE-2026-93857 PUBLISHED

Fireware OS Pre-Authentication Stack Buffer Overflow in SIP Proxy Allows Remote Code Execution

Assigner: WatchGuard
Reserved: 18.09.2026 Published: 27.10.2026 Updated: 27.10.2026

A stack-based buffer overflow vulnerability in Fireware OS's SIP proxy allows a remote, unauthenticated attacker to execute arbitrary code by sending a specially crafted request through a policy that uses the SIP proxy.

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS Score: 9.2

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	Present	Availability	High	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	WatchGuard
Product	Fireware OS
Versions	Default: unaffected affected from 2025.1 to 2026.4 (excl.) affected from 12.0 to 12.12.4 (excl.)

Vendor	WatchGuard
Product	Fireware OS
Versions	Default: unaffected affected from 12.0 to 12.5.22 (excl.)

Affected Configurations

The exploit for this vulnerability requires a SIP proxy configured on the Firebox.

Exploits

WatchGuard is not aware of any exploitation of this vulnerability in the wild.

Solutions

Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22

Credits

Laurent GAFFIE , secorizon.com finder

References

https://psirt.watchguard.com/CVE-2026-93857

Problem Types

CWE-120 CWE
CWE-121 CWE
CWE-787 CWE