Security readout for executives and security teams
Plain-English summary
CVE-2020-29390 lets an unauthenticated attacker run system commands on Zeroshell 3.9.3 through a vulnerable web CGI parameter. For an internet-reachable router or security appliance, that can mean full device compromise. The sources do not name a patch or confirm active exploitation.
Executive priority
Treat as urgent where Zeroshell 3.9.3 is externally reachable. The issue is unauthenticated remote command execution on network infrastructure, but evidence does not confirm active exploitation.
Technical view
Zeroshell 3.9.3 is reported vulnerable in /cgi-bin/kerbynet via the StartSessionSubmit parameter. The CVE description says shell metacharacters and newline encoding can trigger system command execution before authentication. CVSS, CWE, and affected CPE data are not provided in the bundle.
Likely exposure
Exposure is likely limited to environments still running Zeroshell 3.9.3, especially if the web management interface is reachable from the internet or untrusted networks.
Exploitation context
The source bundle includes a public technical write-up, but KEV is false and no cited source confirms active exploitation in the wild.
Researcher notes
The provided record lacks CVSS, CWE, CPE, and patch details. Analysis is based on the CVE description and the referenced public write-up. Avoid assuming other Zeroshell versions are affected without vendor evidence.
Mitigation direction
- Identify and prioritize any Zeroshell 3.9.3 systems.
- Check official vendor or project guidance for fixed or replacement versions.
- Remove web management access from the internet.
- Restrict /cgi-bin/kerbynet access to trusted admin networks only.
- Monitor for suspicious requests to StartSessionSubmit.
Validation and detection
- Inventory network appliances and confirm any Zeroshell 3.9.3 deployments.
- Check whether /cgi-bin/kerbynet is reachable from untrusted networks.
- Review web logs for unusual StartSessionSubmit requests.
- Confirm remediation against vendor or project guidance once available.
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.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-29390 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://blog.quake.so/post/zeroshell_linux_router_rce/CVE 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.