VDB-427421 · CVE-2026-93857 · GCVE-0-2026-93857

WatchGuard Fireware OS SIP proxy buffer overflow

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
10.0	$0-$5k	0.97

Summaryinfo

A vulnerability, which was classified as very critical, has been found in WatchGuard Fireware OS. Impacted is an unknown function of the component SIP proxy. The manipulation leads to buffer overflow. This vulnerability is documented as CVE-2026-93857. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in WatchGuard Fireware OS (affected version unknown). This issue affects an unknown functionality of the component SIP proxy. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at psirt.watchguard.com. The identification of this vulnerability is CVE-2026-93857 since 09/18/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/27/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

WatchGuard

Name

Fireware OS

License

commercial

CPE 2.3info

🔒

CPE 2.2info

🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 10.0

VulDB Base Score: 10.0
VulDB Temp Score: 10.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

09/18/2026 CVE reserved
10/27/2026 +39 days Advisory disclosed
10/27/2026 +0 days VulDB entry created
10/27/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: psirt.watchguard.com
Status: Confirmed

CVE: CVE-2026-93857 (🔒)
GCVE (CVE): GCVE-0-2026-93857
GCVE (VulDB): GCVE-100-427421

Entryinfo

Created: 10/27/2026 17:22
Changes: 10/27/2026 17:22 (63)
Complete: 🔍
Cache ID: 216::103