How severe is CVE-2021-42292?

CVE-2021-42292 has a CVSS score of 7.8/10, rated HIGH. Immediate patching is strongly recommended.

Which products are affected by CVE-2021-42292?

CVE-2021-42292 affects the following products: microsoft 365 apps, microsoft excel, microsoft office, microsoft office 2016, microsoft office 2019, microsoft office 2021.

How do I patch CVE-2021-42292?

No patch has shipped for CVE-2021-42292 yet — track the microsoft 365 apps advisory for a fixed release and apply the workarounds below in the meantime.

How do I detect CVE-2021-42292 across my infrastructure?

Inventory every microsoft 365 apps deployment and check each version against the affected-products list above.

How do I mitigate CVE-2021-42292 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Is CVE-2021-42292 actively exploited in the wild?

Yes. There are 5 known exploit references for CVE-2021-42292, including 4 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-42292?

CVE-2021-42292 has an EPSS (Exploit Prediction Scoring System) score of 43.0%, placing it in the 99th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

Is CVE-2021-42292 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2021-42292 (Microsoft Excel Security Feature Bypass) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2021-11-17. CISA required all US federal civilian agencies to remediate this vulnerability by 2021-12-01. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

Which products and versions are affected by CVE-2021-42292?

CVE-2021-42292 affects microsoft 365 apps; microsoft excel (2 versions, e.g. 2013, 2016); microsoft office (2 versions, e.g. 2013, 2019); microsoft office 2016, and 2 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2021-42292 published, and has it been updated?

CVE-2021-42292 was published on November 10, 2021 and was last updated on August 19, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

CISA KEV · ACTIVELY EXPLOITED

HIGH severity

CVE-2021-42292 — 365 Apps

HIGH

CVE-2021-42292 is a high-severity (CVSS 7.8) vulnerability in microsoft 365 apps. It is in CISA's Known Exploited Vulnerabilities catalog (added 2021-11-17) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

Microsoft Excel Security Feature Bypass Vulnerability

Published

Nov 10, 2021

Updated

Aug 19, 2026

Affected

6 products

Patched

See advisory

Exploits

5 known

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2021-11-17. Federal agencies were required to remediate by 2021-12-01.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2021-42292.

EPSS Exploitation Probability

via FIRST.org ↗

43.0%probability of exploitation in next 30 days

High Risk+11.06%

Lower risk than most CVEs99th percentile — riskier than 99% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-42292 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.

Description

Microsoft Excel Security Feature Bypass Vulnerability

Affected Products

6 products · 15 configurations

Application

365 appsmicrosoft

all

Application

excelmicrosoft

2 versions

20132016

Application

officemicrosoft

2 versions

20132019

Application

office 2016microsoft

all

Application

office 2019microsoft

all

Application

office 2021microsoft

all

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Microsoft Excel Security Feature Bypass Vulnerability

portal.msrc.microsoft.comMSNov 2021

Microsoft Excel Security Feature Bypass Vulnerability

msrc.microsoft.comGoogle-sheetNov 2021

Microsoft Excel Security Feature Bypass Vulnerability

github.comGithubNov 2021

Microsoft Excel Security Feature Bypass Vulnerability

cisa.govCISANov 2021

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every microsoft 365 apps deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2021-42292 yet — track the microsoft 365 apps advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

Microsoft Excel Security Feature Bypass Vulnerability

O3 Security · Runtime Protection

Is CVE-2021-42292 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

Protect my workloads How runtime protection works

CVE-2021-42292 — 365 Apps

Exploitation Status

Actively exploited in the wild

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Description

Affected Products

Detection & mitigation playbook

Detect

Remediation status

Mitigate without a patch

Frequently Asked Questions

Is CVE-2021-42292 being exploited in your environment?