CVE-2026-21514
CVE-2026-21514 is a security flaw in Microsoft Office, part of Microsoft Office. Someone who already has a foothold can use Microsoft Office to take full control of the machine. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 10 Feb 2026.[1]
Microsoft Office is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Fixed in version https://aka.ms/OfficeSecurityReleases and 16.106.26020821.
Description
CISA calls it a word reliance on untrusted inputs in a security decision in Microsoft Office. In its words: “Microsoft Office Word contains a reliance on untrusted inputs in a security decision vulnerability that could allow an authorized attacker to elevate privileges locally.”[1]
The underlying weakness is CWE-807, in MITRE’s list of common software weaknesses.[2]
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| Microsoft 365 Apps for Enterprise | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC 2021 | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC 2024 | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC for Mac 2021 | 16.106.26020821 |
| Microsoft Office LTSC for Mac 2024 | 16.106.26020821 |
Every device with Microsoft Office needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 10 Feb 2026, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 3 Mar 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 2%. That’s in the top 25% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Microsoft has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Update Microsoft Office now.On Windows: Settings, Windows Update, Check for updates, then restart. Office updates come the same way, or from any Office app: File, Account, Update Options. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on https://aka.ms/OfficeSecurityReleases or later.Fixed in version https://aka.ms/OfficeSecurityReleases and 16.106.26020821. Anything older is what attackers are going after.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 2%.[4] |
See also
Other Microsoft Office flaws
- CVE-2009-0238: remote code execution ·
- CVE-2026-21509: security feature bypass ·
- CVE-2009-0556: powerPoint code injection ·
- CVE-2007-0671: excel remote code execution ·
- CVE-2023-23397: outlook privilege escalation ·
- CVE-2023-21715: publisher security feature bypass ·
Other Microsoft flaws
- CVE-2026-96951, Microsoft Windows: command injection ·
- CVE-2026-65660, Microsoft SharePoint: code injection ·
- CVE-2026-85880, Microsoft Windows: heap-based buffer overflow ·
- CVE-2026-81963, Microsoft Windows: link following ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
Added the same day
- CVE-2026-21533, Microsoft Windows: improper privilege management ·
- CVE-2026-21525, Microsoft Windows: NULL pointer dereference ·
- CVE-2026-21519, Microsoft Windows: type confusion ·
- CVE-2026-21513, Microsoft Windows: MSHTML framework protection mechanism failure ·
- CVE-2026-21510, Microsoft Windows: shell protection mechanism failure ·
Every Microsoft flaw on CISA’s list · Everything added in February 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability”. Known Exploited Vulnerabilities Catalog, added 10 Feb 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-21514 Detail”. National Vulnerability Database, published 10 Feb 2026.
- ^ Microsoft. Advisories and fixes: msrc.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.016, percentile 75.6, 31 Oct 2026.
- CVE Program. “CVE-2026-21514”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.