CVE-2021-42292
Microsoft Excel Security Feature Bypass Vulnerability
- CVSS
- 7.8Highscored by the publisher (CNA)
- Exploited in the wild
- Yes, in CISA KEV since 17 Nov 2021CISA deadline for US federal agencies: 1 Dec 2021unvetted proof-of-concept code on github
- EPSS
- 43.0%chance of exploitation in the next 30 daystop 2% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 10 Nov 2021analysed here 12 Nov 2026
Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)
Summary
Triage
- Exploitable
- At runtime
- Attack vector
- local
- Can a WAF block it?
- No. See why
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
| Product | Affected versions | Vendor says fixed in |
|---|---|---|
| Microsoft Microsoft 365 Apps for Enterprise | >= 16.0.1 and < https://aka.ms/OfficeSecurityReleasesVendor says fixed in: not stated | |
| Microsoft Microsoft Excel 2013 Service Pack 1 | >= 15.0.0.0 and < 15.0.5397.1001Vendor says fixed in: not stated | |
| Microsoft Microsoft Excel 2016 | >= 16.0.0.0 and < 16.0.5239.1001Vendor says fixed in: not stated | |
| Microsoft Microsoft Office 2013 Service Pack 1 | >= 15.0.0 and < 15.0.5397.1001Vendor says fixed in: not stated | |
| Microsoft Microsoft Office 2016 | >= 16.0.0 and < 16.0.5239.1001Vendor says fixed in: not stated | |
| Microsoft Microsoft Office 2019 | >= 19.0.0 and < https://aka.ms/OfficeSecurityReleasesVendor says fixed in: not stated | |
| Microsoft Microsoft Office 2019 for Mac | >= 16.0.0 and < 16.55.21111400Vendor says fixed in: not stated | |
| Microsoft Microsoft Office LTSC 2021 | >= 16.0.1 and < https://aka.ms/OfficeSecurityReleasesVendor says fixed in: not stated | |
| Microsoft Microsoft Office LTSC for Mac 2021 | >= 16.0.1 and < 16.55.21111400Vendor says fixed in: not stated |
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
Products named in our analysis
- microsoft:365_apps
- microsoft:excel
- microsoft:office
- microsoft:office_2016
- microsoft:office_2019
- microsoft:office_2021
Fix and mitigation
WAF and other mitigations
Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.
Also consider: patch
Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Listed since 17 Nov 2021.
- CISA due date
- 1 Dec 2021, the remediation deadline for US federal agencies
- CISA required action
- Apply updates per vendor instructions.
- Public exploit code
- Unvetted proof-of-concept code on GitHub: 1 GitHub proof of concept
- CISA SSVC
- exploitation active, automatable no, technical impact totalAssessed by CISA 3 Jan 2024 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
GitHub proofs of concept
- corelight/CVE-2021-4229219 stars
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
Timeline
- 9 Nov 2021First proof-of-concept repository on GitHub (unvetted)
- 10 Nov 2021Published1 day later
- 17 Nov 2021Added to CISA KEV (exploited in the wild)7 days later
- 1 Dec 2021CISA remediation due date (US federal agencies)14 days later
- 3 Jan 2024CISA SSVC assessment: exploitation active764 days (about 2 years) later
- 19 Aug 2026CVE record last updated959 days (about 3 years) later
- 12 Nov 2026Analysed by vulneraibility.com85 days (about 3 months) later
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
| Metric | Value | What it means |
|---|---|---|
| Attack vector | LocalLocal access required (shell, logged-in user). | Local access required (shell, logged-in user). |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | NoneThe attacker needs no prior access. | The attacker needs no prior access. |
| User interaction | RequiredA victim must click, open or otherwise cooperate. | A victim must click, open or otherwise cooperate. |
| Scope | UnchangedImpact stays within the vulnerable component. | Impact stays within the vulnerable component. |
| Confidentiality | HighTotal data disclosure possible. | Total data disclosure possible. |
| Integrity | HighComplete modification possible. | Complete modification possible. |
| Availability | HighFull outage possible. | Full outage possible. |
Common questions
Is CVE-2021-42292 being exploited?
Yes. CVE-2021-42292 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2021-42292?
CVE-2021-42292 is rated High with a CVSS score of 7.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2021-42292?
Yes. A fix has been recorded for CVE-2021-42292. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2021-42292 affect?
CVE-2021-42292 affects microsoft:365_apps, microsoft:excel, microsoft:office, microsoft:office_2016, and 2 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
3 references in the CVE record, grouped by the tags the record gives them.
Patches (1)
- msrc.microsoft.com /update-guide/vulnerability/CVE-2021-42292
Other links (2)
- portal.msrc.microsoft.com /en-US/security-guidance/advisory/CVE-2021-42292
- cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42292
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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