SummaryAI-written · claude-haiku-5-5AI-written · claude-haiku-5-5Written by a language model from the source data on this page. Not reviewed by a person. Generated 23 Oct 2026.
A remote code execution flaw in Microsoft's SMBv3 protocol (Server Message Block 3.1.1) lies in how it handles certain requests, involving improper restriction of operations within the bounds of a memory buffer. An attacker who can reach the affected SMBv3 client or server over the network, without needing credentials or any user interaction, can execute code on the target.
Official description · NVDSource dataSource dataCopied from an authoritative feed: NVD, CVE.org, CISA KEV, FIRST EPSS or MITRE CTID mappings, or labelled by the annotators of a published dataset. Copied from NVD.
A remote code execution vulnerability exists in the way that the Microsoft Server Message Block 3.1.1 (SMBv3) protocol handles certain requests, aka 'Windows SMBv3 Client/Server Remote Code Execution Vulnerability'.
Priority scorePatchfirst’s 0 to 100 ranking. It adds points for CISA KEV listing, ransomware use, EPSS, threat reports, public exploit code and CVSS. Every CVE page shows the breakdown.Breakdown
87.7 / 100
Exploited
Yes, in CISA KEV
Reports
3
Tactics
1/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 3 months after disclosure. Public exploit code (PoC-in-GitHub) was available 4 months before disclosure.
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
1 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order, 4 cited passagesAIAI-writtenWritten by a language model from the source data on this page. Not reviewed by a person.1
Initial AccessTA0001
Exploit Public-Facing ApplicationT1190Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
AI-written · claude-haiku-5-5AI-written · claude-haiku-5-5Written by a language model from the source data on this page. Not reviewed by a person. claude-haiku-5-5: Remote network exploitation of SMBv3 protocol.AI mapping from the description · how it is exploited
Remote network exploitation of SMBv3 protocol
remote code execution vulnerability exists in the way that the Microsoft Server Message Block 3.1.1
These come from early or generic mappings, text matching, or contradict this CVE’s details (for example a public-facing technique on a bug that needs a user to open a file). Shown for completeness.
Exploitation for Client ExecutionT1203AIAI-writtenWritten by a language model from the source data on this page. Not reviewed by a person. claude-haiku-5-5: Remote code execution via protocol request handling.server-side bug exploitable without user interaction; client-execution technique does not fit
Exploitation for Privilege EscalationT1068MachineMachine-matchedFound by keyword or pattern matching over threat-report text. Not reviewed by a person. ATT&CK ID T1068 written in the same sentence as CVE-2020-0796.machine-matched from report text
Detection
0 rules for this CVE · 149 general rules for its techniques
Rules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2020-0796 directly.
CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Named in 3 threat reportsMachineMachine-matchedFound by keyword or pattern matching over threat-report text. Not reviewed by a person. Exact CVE id found in the report text.
3 reportsmcafee.com2ptsecurity.com
Reports are matched by finding the exact id CVE-2020-0796 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.
Four images were there for all to see: an email icon, screenshot from a game with Russian text, screenshot of the site of a game development company, and a screenshot of information about vulnerability CVE-2020-0796 from the Microsoft website.