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CriticalVulnerabilityCVE-2026-93857updated 27 Oct 2026, 19:35 UTC

Firewall SIP proxy can be crashed or taken over by remote attackers

A flaw in the firewall's phone-call (SIP) handling lets an outsider send a specially crafted message that can run their own code on the device, without logging in. Anyone relying on that firewall should update it right away.

Official, 2 sources
SeverityCriticalCVSS 9.2 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Remote attackerNo login or account needed
  2. 2Crafted SIP requestSent through a SIP proxy policy
  3. 3Firewall SIP proxyBuffer overflow on the stack
  4. 4Code executionAttacker runs their own code
  5. ResultAttacker controls the firewall

What happened

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

Why it is dangerous: Successful exploitation would give an attacker code execution on the firewall, which sits at the network edge and controls traffic in and out of the organization. Any organization using SIP proxy policies on affected Fireware OS devices is at risk.

Are you affected?

You are affected if you run a Fireware OS firewall with a policy that uses the SIP proxy.

What to do

  1. Check whether any firewall policy uses the SIP proxy, and if so, check Fireware OS version against the vendor advisory
  2. Apply the vendor's fixed Fireware OS release as soon as it is available to you
  3. Until patched, disable or restrict the SIP proxy policy if it is not needed
  4. Limit exposure of the firewall's SIP traffic to trusted sources where possible

Timeline

  1. 27 Oct 2026, 16:17 UTC
    Publicly disclosed
  2. 27 Oct 2026, 16:17 UTC
    Reported by NVD · NVD
  3. 27 Oct 2026, 16:20 UTC
    Picked up by Zero Radar
  4. 27 Oct 2026, 19:35 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-93857 · GHSA-cjv7-rv7c-h7c2
CVSS
9.2 / 10
EPSS
0.5% chance of exploitation within 30 days
Disclosed
27 Oct 2026, 16:17 UTC
On Zero Radar
27 Oct 2026, 16:20 UTC (3 min after disclosure)
Last change
27 Oct 2026, 19:35 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Firewall SIP proxy can be crashed or taken over by remote attackers · Zero Radar