Pre-authentication code execution via SMBv3 compression overflow
Published Mar 12, 2020 · Updated Aug 12, 2026
Buffer overflow in Microsoft Windows SMBv3 3.1.1 compression allows remote attackers to execute arbitrary code through crafted compressed packets. The compression handler trusts attacker-controlled size and offset fields when allocating a destination buffer, then writes decompressed data beyond that allocation. An unauthenticated network path to TCP port 445 is sufficient on servers with SMBv3 compression enabled; successful exploitation executes code in kernel context.
Summary
What happened
Buffer overflow in Microsoft Windows SMBv3 3.1.1 compression allows remote attackers to execute arbitrary code through crafted compressed packets. The compression handler trusts attacker-controlled size and offset fields when allocating a destination buffer, then writes decompressed data beyond that allocation. An unauthenticated network path to TCP port 445 is sufficient on servers with SMBv3 compression enabled; successful exploitation executes code in kernel context.
The record
- CVE
- CVE-2020-0796
- Published
- Mar 12, 2020
- Updated
- Aug 12, 2026
- Vendor
- Microsoft
- Product
- Windows 10 Version 1909
- Classifications
- CWE-787, T1210
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 12, 2020CVE publishedPublication date reported by the CVE source.
- Aug 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Rapid7 Metasploit SMBv3 Compression Buffer Overflow moduleweaponized · validated
- Jamf SMBleedingGhost Remote Code Execution PoCfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- CISA Known Exploited Vulnerabilities Catalog listingknown exploited catalog
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo