CVE-2021-36380

Sunhillo SureLine before 8.7.0.1.1 allows Unauthenticated OS Command Injection via shell metacharacters in ipAddr or dnsAddr /cgi/networkDiag.cgi.

CVSS: 9.8Criticalscored by CISA
Exploited in the wild: Yes, in CISA KEV since 5 Mar 2024CISA deadline for US federal agencies: 26 Mar 2024
EPSS: 97.8%chance of exploitation in the next 30 daystop 0.1% of scored CVEsFIRST score of 11 Nov 2026
Fix: Not stated by the vendorno fixed release in the CVE record
Published: 13 Aug 2021analysed here 12 Nov 2026

Do first. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. (CISA's required action for this KEV entry)

Summary

Triage

Attack surface: Server-side
Exploitable: At runtime
Attack vector: network
Weakness: CWE-78 OS Command Injection

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Products named in our analysis

sunhillo:sureline

Fix and mitigation

WAF and other mitigations

Can a WAF block it? Partly. The attack is delivered via HTTP request parameters to a specific CGI endpoint, and the malicious input includes shell metacharacters which are unusual and can be detected by a WAF rule. A WAF rule can match /cgi/networkDiag.cgi with shell metacharacters in ipAddr or dnsAddr parameters. No tracked WAF vendor has published a rule for this CVE yet, so you would write it yourself.

What a custom rule would match: /cgi/networkDiag.cgi with shell metacharacters in ipAddr or dnsAddr parameters

Also consider: patch · custom WAF rule · shlex/execve-style APIs

Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Listed since 5 Mar 2024.
CISA due date: 26 Mar 2024, the remediation deadline for US federal agencies
CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Public exploit code: Detection templates only, no public exploit found: 1 Nuclei template
CISA SSVC: exploitation active, automatable yes, technical impact totalAssessed by CISA 5 Mar 2024 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

Nuclei

Sunhillo SureLine <8.7.0.1.1 - Unauthenticated OS Command Injectiondetection template, critical

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

Timeline

13 Aug 2021Published
5 Mar 2024Added to CISA KEV (exploited in the wild)934 days (about 3 years) later
5 Mar 2024CISA SSVC assessment: exploitation activesame day later
26 Mar 2024CISA remediation due date (US federal agencies)21 days later
21 Oct 2025CVE record last updated575 days (about 2 years) later
12 Nov 2026Analysed by vulneraibility.com387 days (about 1 year) later

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Metric	Value	What it means
Attack vector	NetworkReachable over the internet or any routable network.	Reachable over the internet or any routable network.
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	NoneThe attacker needs no prior access.	The attacker needs no prior access.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	UnchangedImpact stays within the vulnerable component.	Impact stays within the vulnerable component.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2021-36380 being exploited?

Yes. CVE-2021-36380 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2021-36380?

CVE-2021-36380 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2021-36380?

Not known from our data. No patch reference has been recorded for CVE-2021-36380, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.

What does CVE-2021-36380 affect?

CVE-2021-36380 affects sunhillo:sureline. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

3 references in the CVE record, grouped by the tags the record gives them.

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA KEV catalog: exploitation, date added, due date
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile
Nuclei templates: detection templates

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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