D621-2: Insufficient Verification of Data Authenticity
CVE-2026-121606 is a critical-severity insufficient verification of data authenticity vulnerability in D621-2 from Qihoo 360, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected D621-2 versions: 6.4.0; 6.4.1; 6.4.2, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.24% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of D621-2 you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Qihoo 360 | D621-2 | 6.4.0; 6.4.1; 6.4.2; 6.4.3; 6.4.4; 6.4.5; 6.4.6; 6.4.7; and 2 more ranges | Not stated |
| Qihoo 360 | D603-2 | 6.4.0; 6.4.1; 6.4.2; 6.4.3; 6.4.4; 6.4.5; 6.4.6; 6.4.7; and 2 more ranges | Not stated |
| Qihoo 360 | D600-2 | 6.4.0; 6.4.1; 6.4.2; 6.4.3; 6.4.4; 6.4.5; 6.4.6; 6.4.7; and 2 more ranges | Not stated |
| Qihoo 360 | D619 | 6.4.0; 6.4.1; 6.4.2; 6.4.3; 6.4.4; 6.4.5; 6.4.6; 6.4.7; and 2 more ranges | Not stated |
| Qihoo 360 | D606-6 | 6.4.0; 6.4.1; 6.4.2; 6.4.3; 6.4.4; 6.4.5; 6.4.6; 6.4.7; and 2 more ranges | Not stated |
| Qihoo 360 | D706 | 6.4.0; 6.4.1; 6.4.2; 6.4.3; 6.4.4; 6.4.5; 6.4.6; 6.4.7; and 2 more ranges | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (vuldb.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (vuldb.com) |
| CVSS 3.1 | 10.0 | Critical | CNA (vuldb.com) |
| CVSS 2.0 | 10.0 | High | CNA (vuldb.com) |
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Insufficient Verification of Data Authenticity
The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
More Insufficient Verification of Data Authenticity vulnerabilities (CWE-345)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Recent Insufficient Verification of Data Authenticity vulnerabilities
- 9.6 Critical severity
- 8.9 High severity
- 7.5 High severity
- 7.5 High severity
- 8.0 High severity
- 7.1 High severity
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