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CVE-2021-36380

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Sunhillo SureLine. For every flaw being used in attacks, see Exploited flaws.

CVE-2021-36380 is a security flaw in Sunhillo SureLine. Attackers can run commands on Sunhillo SureLine from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 5 Mar 2024.[1]

Sunhillo SureLine is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 8.7.0.1.1 of sureline.

Description

CISA calls it an OS command injection vulnerablity in Sunhillo SureLine. In its words: “Sunhillo SureLine contains an OS command injection vulnerability that allows an attacker to cause a denial-of-service or utilize the device for persistence on the network via shell metacharacters in ipAddr or dnsAddr in /cgi/networkDiag.cgi.”[1]

The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.[2]

It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record lists one fixed version: everything before it is affected.[2]

ProductFixed in
sureline8.7.0.1.1

Most families won’t have Sunhillo SureLine; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 5 Mar 2024, 935 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 26 Mar 2024 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 98%. That’s in the top 1% of the flaws it scores.[4]

CISA assesses it as automatable: attackers can run it against many targets at once.

CISA doesn’t say who was attacked, or how.

Fix

Sunhillo has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]

  1. Check whether you use it.Sunhillo SureLine is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 8.7.0.1.1 of sureline), or not in use. CISA gave US government agencies until 26 Mar 2024 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 98%.[4]

See also

Other OS command injection flaws

  • CVE-2026-110447, Collabora Online – Built-in CODE Server: online – built-in CODE server OS command injection ·
  • CVE-2026-106931, EG Secure Solutions SiteGuard Server Edition: OS command injection ·
  • CVE-2026-83549, SonicWall SMA1000 Appliances: OS command injection ·
  • CVE-2026-49869, Kestra OSS: OSS OS command injection ·
  • CVE-2026-73570, Synacor Zimbra Collaboration Suite (ZCS): OS command injection ·

Added the same day

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “Sunhillo SureLine OS Command Injection Vulnerablity”. Known Exploited Vulnerabilities Catalog, added 5 Mar 2024.
  2. ^ National Institute of Standards and Technology. “CVE-2021-36380 Detail”. National Vulnerability Database, published 13 Aug 2021.
  3. ^ Sunhillo. Advisories and fixes: sunhillo.com.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.978, percentile 99.9, 31 Oct 2026.
  5. CVE Program. “CVE-2021-36380”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.