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CVE-2026-20950: Microsoft Excel Remote Code Execution Vulnerability

ROUTINE

Telemetry drift only. No threshold crossed and no authority ruling changed.

CVE record, CISA KEV and EPSS as of 2026-10-18.

CVEs like this one computed, by meaning

What to do now held facts and links

  1. Upgrade to the fixed version for your release line, or later: 16.0.5535.1000; 16.105.26011018; 16.0.10417.20083 CVE record
  2. Record your decision, dated and frozen with today's evidence: patch by a date · mitigated by a compensating control · deferred · accepted the risk · not affected
  3. Check your version against the ranges this record publishes.

What it is stated by the CNA

Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

weakness
CWE-416: Use After Free
affected
Microsoft 365 Apps for Enterprise; Microsoft Excel 2016; Microsoft Office 2019; Microsoft Office LTSC 2021; Microsoft Office LTSC 2024; Microsoft Office LTSC for Mac 2021; Microsoft Office LTSC for Mac 2024; Microsoft Office Online Server
published ranges
microsoft excel 2016; microsoft office 2019; microsoft office long term servicing channel 2021; microsoft office long term servicing channel 2024; and 1 more on the CVE page
fixed in
16.0.5535.1000; 16.105.26011018; 16.0.10417.20083
severity
7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
assigned by
microsoft
published
2026-01-13

check us msrc.microsoft.com

Exploit code held, dated

exploit code
None held in the PoC-in-GitHub feed. A public repository changes this brief.

What moved held, dated

dateEPSSevent
14 Jan 20260.00043
18 Jan 20260.00044
19 Jan 20260.00045
14 Feb 20260.0005
18 Feb 20260.00017
9 Mar 20260.00021
22 Mar 20260.00024
15 May 20260.00039
11 Jun 20260.00022
12 Jun 20260.00021
15 Jun 20260.00429scoring model v2026.06.15
12 Aug 20260.00445
1 Sep 20260.00455
10 Sep 20260.00495
9 Oct 20260.00488

15 observations held. A step marked with a scoring model moved because the measurement was replaced, not because the vulnerability changed.

Outside the record researched, cited

This section reads the record's references and adds cited findings from outside it. It needs an account. Everything above is held facts and is complete without it.

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What would change this brief held, dated

CISA KEV
Not listed in the catalogue we hold. A listing changes this brief.
exploit probability
0.00 on 2026-10-09 (FIRST's EPSS, a probability and not evidence of exploitation). Next band line: 10% (0.10). Crossing a line changes this brief.
fix
Held: 16.0.5535.1000; 16.105.26011018; 16.0.10417.20083. A newer fix from the CNA or OSV changes this brief.

Watch this CVE What counts as a move

How to check this

Every value above is held with two dates: when it was true upstream (as_of) and when we recorded it (tx_from). Re-derive the exploit probability as it stood on any date:

SELECT value, source, source_version, as_of, tx_from
FROM volatile_valid_as_of('CVE-2026-20950', '2026-11-01T23:59:59.999999Z', now());