Fastnetmon: Improper Certificate Validation
CVE-2026-48697 is a high-severity improper certificate validation vulnerability in Fastnetmon from Pavel-odintsov, 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 Fastnetmon versions: 1.2.9 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.16% 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
- Check which version of Fastnetmon 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 |
|---|---|---|---|
| Pavel-odintsov | Fastnetmon | 1.2.9 and earlier | Not stated |
Version data comes from NVD's product matching. 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 3.1 | 7.4 | High | NVD |
| CVSS 3.1 | 7.4 | High | CISA (ADP) |
Official description
FastNetMon Community Edition through 1.2.9 does not verify TLS certificates on outbound HTTPS connections. The execute_web_request_secure() function in src/fast_library.cpp creates a boost::asio::ssl::context with tls_client mode and calls set_default_verify_paths() to load CA certificates, but never calls set_verify_mode(boost::asio::ssl::verify_peer). Without this call, OpenSSL performs the TLS handshake without validating the server's certificate chain, making all HTTPS connections vulnerable to man-in-the-middle attacks. This function is used for telemetry reporting to community-stats.fastnetmon.com, which sends system information including CPU model, kernel version, traffic statistics, and software configuration. An attacker can intercept and modify this data or redirect it to a malicious server.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Certificate Validation
The product does not validate, or incorrectly validates, a certificate.
How developers prevent this class of flaw
- Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
- If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
More Improper Certificate Validation vulnerabilities (CWE-295)
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
Third-party and government advisories
- lorikeetsecurity.com/blog/fastnetmon-cve-2026-48697-missing-tls-validationThird Party Advisory
Other references
Other vulnerabilities in Fastnetmon
- 7.5 High severity
- 8.2 High severity
- 7.5 High severity
- 8.2 High severity
- 8.2 High severity
- 9.8 Critical severity
Recent Improper Certificate Validation vulnerabilities
- 8.1 High severity
- 8.1 High severity
- 8.2 High severity
- 7.1 High severity
- 9.3 Critical severity
- 8.8 High severity
Spotted an error? Tell us.