Out-of-bounds read information disclosure in Microsoft Office Excel
Information is currently not available beyond the provided high-level statement. Provided content indicates CVE-2026-21261 is an out-of-bounds read condition in Microsoft Office Excel that allows an unauthorized attacker to disclose information locally; no additional details about the vulnerable function, parsing context, or triggering file format/feature are included.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An information disclosure vulnerability affecting Microsoft Excel.
A vulnerability in Microsoft Office Excel and Word; specific impact type not provided in the content.
An information disclosure vulnerability in Microsoft Excel.
An information disclosure vulnerability in Microsoft Excel (no additional details provided in the content).
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.