CLICK PLUS C0-0x CPU firmware: Predictable Seed in Pseudo-Random Number Generator (PRNG)
CVE-2025-55069 is a high-severity predictable seed in pseudo-random number generator (PRNG) vulnerability in CLICK PLUS C0-0x CPU firmware from AutomationDirect, with a CVSS 3.1 base score of 8.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version v3.71 as the first without the flaw, so updating CLICK PLUS C0-0x CPU firmware to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.31% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update CLICK PLUS C0-0x CPU firmware to v3.71 or a later version.
- Update CLICK PLUS C0-1x CPU firmware to v3.71 or a later version.
- Update CLICK PLUS C2-x CPU firmware to v3.71 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| AutomationDirect | CLICK PLUS C0-0x CPU firmware | before v3.71 | v3.71 |
| AutomationDirect | CLICK PLUS C0-1x CPU firmware | before v3.71 | v3.71 |
| AutomationDirect | CLICK PLUS C2-x CPU firmware | before v3.71 | v3.71 |
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
- RequiredA user must take an action such as opening a file or link.
- 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
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L. Scored by CNA (hq.dhs.gov).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.7 | High | CNA (hq.dhs.gov) |
| CVSS 3.1 | 8.3 | High | CNA (hq.dhs.gov) |
Official description
A predictable seed in pseudo-random number generator vulnerability has been discovered in firmware version 3.60 of the Click Plus PLC. The vulnerability relies on the fact that the software implements a predictable seed for its pseudo-random number generator, which compromises the security of the generated private keys.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Predictable Seed in Pseudo-Random Number Generator (PRNG)
A Pseudo-Random Number Generator (PRNG) is initialized from a predictable seed, such as the process ID or system time.
How developers prevent this class of flaw
- Use non-predictable inputs for seed generation.
- Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems, or use the more recent FIPS 140-3 if possible.
- Use a PRNG that periodically re-seeds itself using input from high-quality sources, such as hardware devices with high entropy. However, do not re-seed too frequently, or else the entropy source might block.
More Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerabilities (CWE-337)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in CLICK PLUS C0-0x CPU firmware
- 8.3 High severity
Recent Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerabilities
- 8.7 High severity
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