Microsoft
Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability
At a glance
Actively exploited in the wild — prioritise confirming exposure.
High rather than Critical: exposure is scored at a default because we cannot see your systems or suppliers. If you run or depend on Microsoft Office, treat it as Critical.
Briefing
- Do not treat uncorroborated claims as confirmed breaches.
Questions to ask IT
- Do we run Microsoft Office, and which versions?
- Is any of it reachable from the internet?
- Have we checked whether it has already been used against us?
- If it is still not patched, what mitigation is in place, and what is holding the fix up?
Next steps
- Confirm exposure, mitigation status and any service interruption risk.
Vulnerability facts
Full CVE detail CVE-2026-21514- 7.8 · HighExploitable only with local access without any account, but only if a user takes an action, such as opening a file or link. High impact on confidentiality, integrity and availability.CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Listed: attacks using it have been seen (on the catalogue since )
- ~1.6% estimated chance of attack in 30 days
No technical write-up beyond these facts and the summary below yet.
Next steps
- Confirm whether affected products/versions are present and prioritise patching or mitigations
Summary
- Microsoft Office Word contains a reliance on untrusted inputs in a security decision vulnerability that could allow an authorised attacker to elevate privileges locally.
- CVE-2026-21514 is listed in known-exploited catalogue (exploitation in the wild)
- Authoritative catalogues report active exploitation of this vulnerability.
Why this matters in the UK
- Known-exploited catalogue reports exploitation in the wild
Products and services involved
- Microsoft Office98% match confidence · CVE-2026-21514
Pulse
Last checked 4d ago · Recheck overdue since 5 Nov 2026, 22:04 UK time · 4 quiet checks collapsed
in the next 30 days first recorded at 1.5% (lower likelihood signal, not confirmed exploitation).
recorded — watch for changes; not confirmed exploitation.
2 quiet checks hidden.
Sources
Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability
How we know
Statements extracted from sources. Higher confidence means stronger corroboration.
- ConfirmedHeadline90% confidence
Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability
- ConfirmedSummary fact75% confidence
Microsoft Office Word contains a reliance on untrusted inputs in a security decision vulnerability that could allow an authorised attacker to elevate privileges locally. Affects Microsoft Office. Known ransomware campaign use: Unknown. 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.
- ConfirmedCVE identifier95% confidence
Event involves CVE-2026-21514
- ConfirmedKnown-exploited catalogue98% confidence
CVE-2026-21514 is listed in known-exploited catalogue (exploitation in the wild)