Microsoft SharePoint Server Remote Code Execution Vulnerability

published 2021-12-15 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-29284

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 2.9%; EPSS 2.9% chance of exploitation in 30 days, percentile 87%
public exploits: 0; none known

Patch / fix

fixed in 4 links 1

Microsoft Microsoft SharePoint Enterprise Server 2016 16.0.5254.1000
Microsoft Microsoft SharePoint Server 2019 16.0.10381.20001
Microsoft Microsoft SharePoint Server Subscription Edition 16.0.14326.20620
Microsoft Microsoft SharePoint Foundation 2013 Service Pack 1 15.0.5407.1000

portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42309 advisory

Exploit prediction

2.93% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	6.5	AV:N/AC:L/Au:S/C:P/I:P/A:P

Affected products

Microsoft Microsoft SharePoint Enterprise Server 2016
Microsoft Microsoft SharePoint Server 2019
Microsoft Microsoft SharePoint Server Subscription Edition
Microsoft Microsoft SharePoint Foundation 2013 Service Pack 1

Classification

Weakness

CWE-94 Improper Control of Generation of Code
CWE-732 Incorrect Permission Assignment for Critical Resource

References

portal.msrc.microsoft.com /en-US/security-guidance/advisory/CVE-2021-42309
patch, vendor-advisory
zerodayinitiative.com /advisories/ZDI-22-074/
third-party-advisory, vdb-entry

Sources

CVE List CVE-2021-42309
NVD CVE-2021-42309

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary