CVE-2021-21509Patch

MEDIUM

Exploitation ongoing with high activity in latest observed window (1 mentions)

Immediate actions

Patch affected systems immediately
Assume compromise if assets are exposed

Recommended action window: Immediate (within 24h)

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4.0/ 10 priority

Priority

MEDIUM

Exploitation

ACTIVE

PoC

NONE

Patch

AVAILABLE

Momentum

NONE

Threat summary

Active exploitation appears in 1 classified signals
Patch or workaround signal is available
1 mentions across 1 observed day

What's happening

Active exploitation reported across 1 signal
Patch or workaround mentioned in 1 signal
Technical details provided in 1 signal
1 total mentions across 1 day

Deep dive

Activity timeline1 mentions / 1d

Signal classification1 categories

Patch

1100.0%

Full discourse1 post

Progressive Robot@ProgresiveRobot257d
Patch
Microsoft has issued an emergency patch for a zero-day vulnerability (CVE-2021-21509) in Office, allowing attackers to bypass OLE mitigations and execute malware. CISA has included the flaw in their KEV catalog. #Microsoft #Office #SecurityPatch #ZeroDayVulnerability https://t.co/WMeToNOuIK
Post summary
Microsoft released an emergency patch for CVE‑2021‑21509, a zero‑day in Office, and CISA flagged it as known exploited, confirming active attacks in the wild.
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