NCSC-2026-0039

Vulnerability from csaf_ncscnl - Published: 2026-01-27 07:27 - Updated: 2026-01-27 07:27
Summary
ZeroDay kwetsbaarheid verholpen in Microsoft Office

Notes

The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this page to enhance access to its information and security advisories. The use of this security advisory is subject to the following terms and conditions: NCSC-NL makes every reasonable effort to ensure that the content of this page is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or continuous keeping up-to-date. The information contained in this security advisory is intended solely for the purpose of providing general information to professional users. No rights can be derived from the information provided therein. NCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of this security advisory. This includes damage resulting from the inaccuracy of incompleteness of the information contained in the advisory. This security advisory is subject to Dutch law. All disputes related to or arising from the use of this advisory will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings.
Feiten
Microsoft heeft een ZeroDay kwetsbaarheid verholpen in Microsoft Office.
Interpretaties
De kwetsbaarheid bevindt zich in de wijze waarop Microsoft Office omgaat met onbetrouwbare invoer, wat aanvallers in staat stelt om beveiligingsfuncties lokaal te omzeilen. Dit kan de integriteit van beveiligingsbeslissingen die door de software worden genomen, beïnvloeden. De afhankelijkheid van onbetrouwbare invoer creëert een pad voor potentiële exploitatie, wat kan leiden tot ongeautoriseerde toegang of acties binnen de getroffen systemen. Voor succesvol misbruik moet de kwaadwillende lokale toegang tot het kwetsbare systeem hebben. Dit kan ook mogelijk worden verwezenlijkt door het slachtoffer te misleiden een malafide document te openen. Microsoft geeft aan op de hoogte te zijn dat exploitcode gedeeld wordt. De exploitcode is (nog) niet publiek beschikbaar. Het Amerikaanse CISA heeft de kwetsbaarheid op de Known Exploited Vulnerabilities-lijst geplaatst, wat inhoudt dat misbruik van de kwetsbaarheid is bevestigd bij een Amerikaanse Federale overheids-organisatie.
Oplossingen
Microsoft heeft updates uitgebracht om de kwetsbaarheid te verhelpen voor Office 2021. Voor Office 2016 en 2019 zijn (nog) geen updates beschikbaar, maar deze worden zeer spoedig verwacht. Wel zijn er mitigerende maatregelen beschikbaar om het risico van misbruik zoveel mogelijk te beperken. Zie bijgevoegde referenties voor meer informatie.
Kans
medium
Schade
high
CWE-807
Reliance on Untrusted Inputs in a Security Decision
To clipboard 

{
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    "distribution": {
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    "lang": "nl",
    "notes": [
      {
        "category": "legal_disclaimer",
        "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this page to enhance access to its information and security advisories. The use of this security advisory is subject to the following terms and conditions:\n\n    NCSC-NL makes every reasonable effort to ensure that the content of this page is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or continuous keeping up-to-date. The information contained in this security advisory is intended solely for the purpose of providing general information to professional users. No rights can be derived from the information provided therein.\n\n    NCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of this security advisory. This includes damage resulting from the inaccuracy of incompleteness of the information contained in the advisory.\n    This security advisory is subject to Dutch law. All disputes related to or arising from the use of this advisory will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings."
      },
      {
        "category": "description",
        "text": "Microsoft heeft een ZeroDay kwetsbaarheid verholpen in Microsoft Office.",
        "title": "Feiten"
      },
      {
        "category": "description",
        "text": "De kwetsbaarheid bevindt zich in de wijze waarop Microsoft Office omgaat met onbetrouwbare invoer, wat aanvallers in staat stelt om beveiligingsfuncties lokaal te omzeilen. Dit kan de integriteit van beveiligingsbeslissingen die door de software worden genomen, be\u00efnvloeden. De afhankelijkheid van onbetrouwbare invoer cre\u00ebert een pad voor potenti\u00eble exploitatie, wat kan leiden tot ongeautoriseerde toegang of acties binnen de getroffen systemen.\n\nVoor succesvol misbruik moet de kwaadwillende lokale toegang tot het kwetsbare systeem hebben. Dit kan ook mogelijk worden verwezenlijkt door het slachtoffer te misleiden een malafide document te openen.\n\nMicrosoft geeft aan op de hoogte te zijn dat exploitcode gedeeld wordt. De exploitcode is (nog) niet publiek beschikbaar. Het Amerikaanse CISA heeft de kwetsbaarheid op de Known Exploited Vulnerabilities-lijst geplaatst, wat inhoudt dat misbruik van de kwetsbaarheid is bevestigd bij een Amerikaanse Federale overheids-organisatie.",
        "title": "Interpretaties"
      },
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        "text": "Microsoft heeft updates uitgebracht om de kwetsbaarheid te verhelpen voor Office 2021. Voor Office 2016 en 2019 zijn (nog) geen updates beschikbaar, maar deze worden zeer spoedig verwacht. Wel zijn er mitigerende maatregelen beschikbaar om het risico van misbruik zoveel mogelijk te beperken. Zie bijgevoegde referenties voor meer informatie.",
        "title": "Oplossingen"
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      {
        "category": "general",
        "text": "Reliance on Untrusted Inputs in a Security Decision",
        "title": "CWE-807"
      }
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        "summary": "Reference",
        "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509"
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}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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