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CVE-2026-40694VulnerabilityPublished

Microsoft · Out-of-bounds write for some Hyperscan before version v5.4.2.1 within Ring 3: User Applications may allow a denial of

Affects MicrosoftSource GCVE Database

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Authoritative record:CVE-2026-40694· Medium 5.8

Not known to be exploited · CVSS 5.8 Medium.

Data as of 13 Nov 2026, 10:28 UTC

CVSS 4.0 base score
5.8Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (intel)CVSS 4.05.8
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
HyperscanAffected
  • =before version v5.4.2.1
Fixed in–

AI-suggested

Users should monitor Microsoft Security Response Center updates for remediation information.

Description

An out-of-bounds write vulnerability exists in some versions of Hyperscan before v5.4.2.1, specifically affecting version 3.0. This flaw could potentially allow user applications running in Ring 3 to cause a denial of service. The vulnerability is tracked as CVE-2026-40694 and is associated with Microsoft products. No CVSS score or detailed impact information is provided.

References

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