Security readout for executives and security teams
Plain-English summary
This issue weakens pfSense’s temporary blocking behavior for abusive SSH activity. In pfSense 2.4.4_1, expiretable block durations may not match sshguard’s intended block durations, so blocks can expire earlier or behave differently than administrators expect.
Executive priority
Treat this as a configuration-control weakness rather than a confirmed critical exploit. Prioritize exposed firewall administration interfaces and legacy pfSense 2.4.4_1 systems, especially where temporary blocking is a primary defense.
Technical view
CVE-2018-20798 describes an expiretable configuration mismatch in pfSense 2.4.4_1 relative to sshguard’s block durations. The reported effect is easier bypass of intended access restrictions. No CVSS score, CWE, affected CPE list, patch details, or confirmed exploitation evidence are provided in the source bundle.
Likely exposure
Exposure appears most relevant to pfSense 2.4.4_1 deployments relying on sshguard and expiretable-based temporary blocks for SSH access restriction. The source bundle does not provide broader affected-version data.
Exploitation context
The sources do not show CISA KEV listing or confirmed active exploitation. The plausible risk is operational: repeated abusive access attempts may face shorter or inconsistent blocking than intended.
Researcher notes
Evidence is thin: the CVE description and Redmine reference identify the mismatch and potential bypass, but do not provide CVSS metrics, affected CPEs, exploit reports, or remediation text in the supplied bundle.
Mitigation direction
- Check Netgate/pfSense guidance for issue 9223 and any supported corrective update.
- Verify whether any pfSense 2.4.4_1 systems remain in service.
- Review sshguard and expiretable settings for block-duration alignment.
- Restrict administrative services to trusted networks or VPN paths.
- Increase monitoring for repeated SSH authentication failures.
Validation and detection
- Inventory pfSense versions and identify any 2.4.4_1 installations.
- Confirm whether sshguard and expiretable are enabled on exposed systems.
- Compare configured expiretable durations with intended sshguard block behavior.
- Review logs for repeated attempts allowed sooner than expected.
- Document vendor guidance applied or note that guidance was unavailable.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2018-20798 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://redmine.pfsense.org/issues/9223CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.