DCS-6517: Use of Insufficiently Random Values
CVE-2025-6931 is a high-severity use of insufficiently random values vulnerability in DCS-6517 from D-Link, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected DCS-6517 versions: 2.02. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.23% chance of exploitation within 30 days, higher than 83% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of DCS-6517 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 |
|---|---|---|---|
| D-Link | DCS-6517 | 2.02 | Not stated |
| D-Link | DCS-7517 | 2.02 | Not stated |
| D-Link | Dcs-6517 Firmware | 2.02.0 and earlier | Not stated |
| D-Link | Dcs-7517 Firmware | 2.02.0 and earlier | 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
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 2.9 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 3.7 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 7.4 | High | NVD |
| CVSS 2.0 | 2.6 | Low | CNA (vuldb.com) |
Official description
A vulnerability classified as problematic was found in D-Link DCS-6517 and DCS-7517 up to 2.02.0. Affected by this vulnerability is the function generate_pass_from_mac of the file /bin/httpd of the component Root Password Generation Handler. The manipulation leads to insufficient entropy. The attack can be launched remotely. The complexity of an attack is rather high. The exploitation appears to be difficult. The exploit has been disclosed to the public and may be used. This vulnerability only affects products that are no longer supported by the maintainer.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Insufficiently Random Values
The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.
How developers prevent this class of flaw
- Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds. In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts. Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a random enough number.
- Consider a PRNG that re-seeds itself as needed from high quality pseudo-random output sources, such as hardware devices.
- Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems. Consult FIPS 140-2 Annex C (Approved Random Number Generators).
More Use of Insufficiently Random Values vulnerabilities (CWE-330)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vuldb.com/?id.314443Third Party Advisory, VDB Entry
- vuldb.com/?submit.605592Third Party Advisory, VDB Entry
- vuldb.com/?submit.605593Third Party Advisory, VDB Entry
- vuldb.com/?submit.605596Third Party Advisory, VDB Entry
Technical write-ups (may include proof of concept)
- cdn2.v50to.cc/dlink/DCS-6517B1_FW_v2.02.01/report_3.pdfExploit, Third Party Advisory
- cdn2.v50to.cc/dlink/DCS-7517_B1_FW_v2.02.01/report_1.pdfExploit, Third Party Advisory
Other references
- vuldb.com/?ctiid.314443Permissions Required, VDB Entry
- dlink.com/Product
Recent Use of Insufficiently Random Values vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.1 High severity
- 8.1 High severity
- 8.0 High severity
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