CVE-2021-27561 Yealink Device Management: command or code injection
In plain words: The program treats text it receives as instructions instead of plain data. The attacker can run commands on the machine — often the whole device is taken over.
Confirmed exploited by CISA on · US federal patch deadline Nov 17, 2021
What to do
- Install Yealink's security update for Device Management. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Keep a list of every internet-facing server you run so nothing is forgotten.
- Patch anything in this catalog first, ahead of normal patch cycles.
- Put admin and file-transfer apps behind a VPN or single sign-on instead of the open internet.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: Mass data theft and ransomware: a single flaw in a file-transfer or email server has exposed thousands of organisations at once.
The details
- Official name
- Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability
- Product
- Yealink Device Management
- CISA description
- Yealink Device Management contains a server-side request forgery (SSRF) vulnerability that allows for unauthenticated remote code execution.
- Type of flaw
- Command or code injection (CWE-78)
- Confirmed exploited
- Nov 3, 2021
- US federal patch deadline
- Nov 17, 2021
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Answering about CVE-2021-27561 ·
Questions about CVE-2021-27561
Is CVE-2021-27561 being exploited?
Yes. CISA added CVE-2021-27561 to its Known Exploited Vulnerabilities catalog on Nov 3, 2021, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2021-27561?
Install Yealink's security update for Device Management. If no update exists, follow the vendor's workaround or stop using the product until one ships. Keep a list of every internet-facing server you run so nothing is forgotten.
Am I affected by CVE-2021-27561?
Only if you use Yealink Device Management. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.