CVE-2026-121606Qihoo 360 D621-2 insufficient verification of data authenticity
CVE-2026-121606 is a insufficient verification of data authenticity in Qihoo 360 D621-2, rated critical (9.3 on CVSS 4.0).
Why this priority: Critical, and reachable over the network without an account.
Published · Updated · NVD status: Deferred
What it is
Data is accepted without proof it came from where it claims. A cryptographic signature is not checked properly, so forged data is accepted.
How it is reached
An attacker can exploit it over the network, without an 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 read or tamper with traffic, or pass a forged message as genuine. The damage can spread past the vulnerable component into others.
Is it being exploited?
CISA's SSVC assessment notes a public proof of concept. It can be exploited automatically, at scale. EPSS estimates a 0.24% chance of exploitation activity in the next 30 days, higher than 15% of scored CVEs.
What to do
- No fixed version is listed yet. Find every place Qihoo 360 D621-2 runs, watch the references for a fix, and plan a replacement if it is no longer supported.
- While there is no fix, keep it off the internet or behind a VPN, allowlist or authenticating proxy.
Description from NVD
A vulnerability has been found in Qihoo 360 D621-2, D603-2, D600-2, D619, D606-6 and D706 up to 6.4.9. Affected by this issue is the function verify_sign of the file fs2/bin/iscm of the component Firmware Signature Verification. Such manipulation of the argument sign leads to improper verification of cryptographic signature. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
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
- TLS termination and service-to-service channels. The flaw sits on the network path between clients and services.
- Signature checks. The flaw sits on the network path between clients and services.
Trust boundaries in play
- Internet-facing entry points. No account is needed. Any instance reachable from outside your perimeter, through a load balancer, gateway, VPN or exposed admin port, is in scope.
- Isolation between components. The impact crosses out of the vulnerable component into others it should be isolated from.
- On the network path between clients and services. An attacker who crosses it can read or tamper with traffic, or pass a forged message as genuine.
Questions to answer about your own systems
- Where does Qihoo 360 D621-2 run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- 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.