Used in attacks· fix by 2022-08-1010.0CriticalUsed by ransomware gangs
Microsoft SMBv3
CVE-2020-0796
A remote code execution vulnerability exists in the way that the Microsoft Server Message Block 3.1.1 (SMBv3) protocol handles certain requests. An attacker who successfully exploited the vulnerability could gain the ability to execute code on the target server or client.
What this means for your business
- It affects Microsoft SMBv3. It matters if your company, or a supplier that handles your data, runs it.
- Attackers are already using it. CISA added it to its list of flaws used in real attacks on 10 February 2022.
- Ransomware gangs are known to have used it.
- An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 100% chance of attack attempts being seen in the next 30 days, ranking above 99% of all known flaws.
What to do
- 1Check whether your company or your suppliers run Microsoft SMBv3, and which version. The affected versions are listed further down this page.
- 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
- 3Treat it as urgent. US federal agencies must fix it by 10 August 2022. That deadline does not apply to private companies, but it shows how seriously CISA takes it.
- 4Because attackers have used it, check the affected systems for signs of a break-in, not only for the update.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Required action
Apply updates per vendor instructions.
CISA’s wording, unedited.
Scoring
- CVSS
- 10.0 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H- Weakness
- CWE-119
- Assigned by
- secure@microsoft.com
Dates
- Published
- 2022-02-10
- Last modified
- 2026-08-12
- Added to KEV
- 2022-02-10
- Remediation due
- 2022-08-10
- Sources
- CISA KEV, NVD
Affected products
- Microsoft Windows 10 1903all versions
- Microsoft Windows 10 1909all versions
- Microsoft Windows Server 1903all versions
- Microsoft Windows Server 1909all versions
As listed in the NVD configuration data. Not a statement about your estate.
References
- http://packetstormsecurity.com/files/156731/CoronaBlue-SMBGhost-Microsoft-Windows-10-SMB-3.1.1-Proof-Of-Concept.html
- http://packetstormsecurity.com/files/156732/Microsoft-Windows-SMB-3.1.1-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/156980/Microsoft-Windows-10-SMB-3.1.1-Local-Privilege-Escalation.html
- http://packetstormsecurity.com/files/157110/SMBv3-Compression-Buffer-Overflow.html
- http://packetstormsecurity.com/files/157901/Microsoft-Windows-SMBGhost-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/158054/SMBleed-SMBGhost-Pre-Authentication-Remote-Code-Execution-Proof-Of-Concept.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0796
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-0796